CHAPTER LV
ROBERT GROSSETESTE
Chief sources for Robert Grosseteste—Reasons for Roger Bacon’s eulogy—Grosseteste’s scholarly career—His writings: absence of magic—His scientific writings little affected by his ecclesiastical position—Reliance on experience—Theory of vision and science of perspective—Experimental discovery of lenses—Mentioned also in The Romance of the Rose—Theories formed by experimenters with lenses—Mathematical physics: the radiation of virtue—The Computus and calendar reform—Juggling with numbers—From mathematics to astronomy to astrology—Astrology in natural philosophy, agriculture, alchemy, medicine and music—Some astrological technical detail—Man and the stars—Grosseteste’s theory of comets—Alchemy—Other treatises—Summa philosophiae ascribed to Grosseteste—Its contents—Oriental origin of philosophy—Greek men of learning—Arabs and medieval Christians—Ancient and modern science compared—Criticism of Aristotle and the Arabic text—Use of the word “modern”—Theology, philosophy, and science; speculative and experimental—Astrology in the Summa—Occult virtue and alchemy—Brother Giles on the comet of 1264—Appendix I. The Perspective or Optics of Witelo.
Chief sources for Robert Grosseteste.
The fame of Robert Grosseteste,[1421] who lived from about 1175 to 1253 and was bishop of Lincoln during the last eighteen years of his life, rests largely upon the praises of his countrymen and contemporaries, Matthew Paris and Roger Bacon, and upon his own writings. The historian, Matthew Paris, depicts him especially as the man of affairs, the churchman and statesman who dared oppose either king or pope for England’s sake. But with his repeated resistance in parliament to royal financial exactions, his outspokenness against abuses at the papal court and his refusal to admit papal provisors to benefices in his diocese, his aggressive and reforming activity in his bishopric and consequent quarrels with the monastic orders and his own cathedral chapter—with all this side of his career we are little concerned. It is rather as a great scholar of his time that like Roger Bacon we shall look back upon him.
Reasons for Roger Bacon’s eulogy.
Bacon’s eulogies of Grosseteste may seem rather extravagant. Writing fourteen years after his death he thinks that no living scholar can compare with him, nay, he ranks him and Adam Marsh, another Englishman of whom we know little, as in their day what Solomon, Aristotle and Avicenna were in theirs.[1422] One reason for this high praise is presumably that Grosseteste had been Bacon’s favorite teacher, and certainly that he was interested in the same learned pursuits, Greek and Hebrew, mathematics, optics, experimental science, as the friar who followed him. Roger practically admits that he owes much in those fields to Robert and an examination of Grosseteste’s writings makes this fact still more evident.
Grosseteste’s scholarly career.
A letter by Giraldus Cambrensis written before the close of the twelfth century speaks of the then youthful Grosseteste as already proficient in law and medicine. He seems to have been born of humble and poor parents at Stradbrook in Suffolk.[1423] He was educated at Oxford where he became rector scholarum and Chancellor and in 1224 the first rector of the Franciscans at Oxford. He perhaps also studied at Paris. After holding various archdeaconries and other prebends he was elected bishop of Lincoln in 1235 but continued his interest in the welfare of the university at Oxford. Roger Bacon, in affirming that Grosseteste surpassed all others in knowledge of the sciences, gives as a reason his long life and experience as well as his enthusiasm for study;[1424] and in another passage declares that hitherto it has taken thirty or forty years for a man to become really proficient in mathematics, as the case of Robert Grosseteste among others shows.[1425] Bacon also states that it was not “until the latter portion of his life” that he undertook the work of making translations and summoned Greeks and had grammars brought from Greece and other lands. Since Grosseteste appears at first to have studied law and medicine rather than ancient languages and mathematical sciences, Bacon’s statements suggest that the works of Grosseteste which we are about to consider were written late in life. This inference is further borne out by a passage in the treatise De impressionibus aeris seu de prognosticatione which gives the positions of the seven planets in the signs of the zodiac and states the date as “the Arabic year 646 or the year of grace 1249.”[1426]
His writings: absence of magic.
Our discussion of Grosseteste will be based upon some treatises included in Baur’s edition of his philosophical works. They are mostly brief and in some cases seem rather fragmentary. We shall not be concerned with his Greek grammar or with his theological writings, which occupy half of the bibliography in Pegge’s Life.[1427] His letters contain some hints of his scientific works but nothing bearing on magic or astrology. It used to be stated that Grosseteste certainly constructed charms to expel maladies, that he invented forms of words to exorcise fiends, and that he worked cures by engraved gems.[1428] The ascription to Grosseteste of treatises on Necromancy and Sorcery, and the Philosopher’s Stone, is, however, false and grew, Baur says, from marginal glosses appended to one of his genuine works.[1429] What we shall note in Grosseteste’s works will be mainly his attitude to experimental science on the one hand and to astrology on the other.
Scientific writings little affected by his ecclesiastical position.
In these scientific treatises by Grosseteste there is little to suggest the Christian bishop. However, in the work “On the Fixity of Motion and Time” he opposes the Aristotelian doctrine that the universe or motion of the celestial bodies is eternal.[1430] And in a second treatise, “On the Order of the Emanation of Things Caused from God,” he expresses the wish that men would cease to question the scriptural account of the age and beginning of the world.[1431] A third treatise “On Freedom of the Will” also lies on the frontier of philosophy and theology.
Reliance on experience.
Grosseteste affords us further examples in a number of passages of that reliance upon experience and reason, that rejection of certain views as contrary to experience, and yet that acceptance of statements in old authors as based upon experience, which we saw in Galen and William of Auvergne’s “experimental books,” and shall see in Albertus Magnus and the other medieval scientists. Grosseteste speaks, however, not merely of experience or experimenta, but also of experimenters (experimentatores).[1432] We may first note some use of observation and experience in astronomy and geography. In his treatise on comets he alludes to “experience in natural things.”[1433] In his treatise on the Sphere[1434] Bishop Robert declares that the sphericity of the earth and of all the stars and planets “is shown both by natural reasons and astronomical experiences,” that is, in the case of the earth, by the observations of the sky by men in different parts of the earth. In the same work he says that Thabit ben Corra (836-901 A. D.) working over the operations of Ptolemy, “found by certain experiments that the motion of the fixed stars was different.”[1435] Likewise in his treatise On the Generation of the Stars Grosseteste remarks of one contention that “experience shows the contrary” and of another view that it “is against both experience and reason.”[1436] Again in writing Of the Nature of Places he adduces in support of his positions “experiments and reasons,” and “divers authors and experimenters.”[1437] The old legend of the Hyperboreans who dwell among mountains near the pole in such a salubrious and temperate climate that they live on and on until they tire of life and commit voluntary suicide by leaping off cliffs into the sea, Grosseteste introduces by the statement: “It has also been found by experience, as authors tell”—among whom he names Pliny, Solinus, and “Marcianus in his geometry.”
Theory of vision and science of perspective.
In the realm of physics Grosseteste not only mentions experience in discussing vision and what he calls Perspective but also brings to our notice a recent or approaching experimental discovery, that of magnifying lenses. In his treatise on the rainbow he makes a rather unpromising beginning. After arguing whether the sense of sight operates by the eye receiving something within itself, as natural philosophers are prone to hold, or by sending forth a visual species or rays, he decides as was usual with men of his time in favor of the latter alternative.[1438] He cites Aristotle in his last book on animals as saying that a man with deep-set eyes sees farther because his visual virtue is not spread or scattered but goes straight—as if from a long-barreled gun—to the things seen.
Experimental discovery of lenses.
Grosseteste then goes on to say that there are three parts of Perspective. The first is that concerning the sight with which he has just been dealing. The second concerns mirrors. The third has been “untouched and unknown among us until the present time. Yet we know that Aristotle completed this third part”—he of course did nothing of the sort—“and that it is much more difficult in its subtlety and far more wonderful in its profound knowledge of natures than the other parts. For this branch of Perspective thoroughly known shows us how to make things very far off seem very close at hand and how to make large objects which are near seem tiny and how to make distant objects appear as large as we choose, so that it is possible for us to read the smallest letters at an incredible distance, or to count sand or grain or grass or any other minute objects.”[1439] So far the passage reads as if it might be merely the exaggerated dream of fancy. But Grosseteste proceeds to state “how these marvels happen,” which seems to be by the breaking up of “the visual ray”—or as we should say, by the refraction of rays of light—as it passes through several transparent objects or lenses of varying nature. He explains also that great distance does not make an object invisible but the narrowness of the angle under which it is seen.[1440] This he proceeds to illustrate “by experiments” (per experimenta). Again in his treatise on comets he mentions “those who have experienced that by a transparent figure interposed between the spectator and the object seen it is possible that the thing seen should be multiplied and that great things seem small and conversely according to the shape given the interposed transparent object.”[1441] I have given as far as possible a literal translation of Grosseteste’s words on this point in order to convey his exact or inexact meaning. If these passages are not a sufficient proof that magnifying lenses of some sort were already discovered, they at least point the way to the microscope and telescope, and we know that eye-glasses for nearsightedness were in use at the latest by the end of the thirteenth century.
Mentioned also in The Romance of the Rose.
Very similar and perhaps copied from this very treatise of Grosseteste on the rainbow—or from its source (Al-Hazen)—are some verses in the continuation of the French Romance of the Rose written by Jean de Meun, probably about 1270. Besides remarking of rainbows that—the words are Ellis’ translation—[1442]
“Only he who’s learned the rule
Of optics in some famous school
Can to his fellow men explain
How ’tis that from the sun they gain
Their glorious hues;”
the poet mentions burning-glasses and various types of mirrors, and also tells us that from optics one
“... may learn the cause
Why mirrors, through some subtle laws
Have power to objects seen therein—
Atoms minute or letters thin—
To give appearance of fair size,
Though naked unassisted eyes
Can scarce perceive them. Grains of sand
Seem stones when through these glasses scanned.”
The poet adds that by these glasses one can read letters from such a distance that one would not believe it unless he had seen it. Then he concludes:
“But to these matters blind affiance
No man need give; they’re proved by science.”
Theories formed by experimenters with lenses.
Returning to Grosseteste and experimental method we may note his mention in the same treatise upon comets of “those who reflect and experiment in natural phenomena and form their opinions from their experiments without foundation of reasons.”[1443] Grosseteste holds that such experimenters “necessarily fall into false notions concerning the natures of comets,” because they try to explain them as reflected rays and the like after the analogy “of their varied experiments which they have employed in radiations and the producing of fires”—probably by burning glasses—“and by what is seen through the medium of lenses” (diaphanorum). The important point for us, however, is not whether these men were wrong about comets, but their varied experimentation and their basing of hypothesis upon their experiments.
Mathematical physics: the radiation of virtue.
In view of Grosseteste’s interest in physical and astronomical matters, and his training, if we believe Bacon, for some thirty or forty years in mathematics, it is not surprising that he realized something of the value of mathematics in the study of natural science. He believed that a knowledge of geometry was of great aid to the “diligent investigator of natural phenomena” in explaining the causes of all natural effects. In a treatise “On lines, angles and figures,” or “On refraction and reflexion of rays,” Grosseteste holds that not only vision or light but every natural agent sends forth its virtue to the object affected and acts upon sense or matter along geometrical lines.[1444] This doctrine of radiation or emanation of force seems to date back at least to Plotinus, and we have heard Alkindi among the Arabs in his treatise on Stellar Rays say that the stars and all objects in the world of the four elements emit rays of this sort. From any given agent virtue radiates forth in all directions, but a perpendicular line is the shortest and strongest line of force between it and any other single point or object. From a point or center of influence to a larger surface we get pyramids or cones of radiated force. The same theory is set forth by Roger Bacon under the name “multiplication of species” but even this wording is not new with him, since Grosseteste speaks of the natural agent as “multiplying its virtue” from itself to the thing affected, and then explains that this virtue is also sometimes called “species” and sometimes “similitude” and is the same in whatever way it is named.
The Computus and calendar reform.
The Computus, or treatise on reckoning time and keeping track of Easter especially and also other church festivals, had been a variety of mathematical and astronomical exercise indulged in by the clergy even in the darkest periods of the early middle ages. The Computus of Grosseteste pointed out the need of reforming the Julian calendar then in use, and he also called attention to this need in his treatise on The Sphere. From the later use made of it by Roger Bacon[1445] and by Cardinal Pierre d’Ailly[1446] in the early fifteenth century one infers that Grosseteste’s Computus remained an authoritative work upon the subject of calendar reform.[1447]
Juggling with numbers.
On one occasion at least Grosseteste’s interest in mathematics degenerated into one of those puerile reveries on the relations and perfection of certain numbers in which so many authors since Pythagoras, if not before him, had indulged. Having stated that in “the supreme body” there are four things, namely, form, matter, composition and compound, Grosseteste states that form is represented by the number one, matter by two, and composition by three, “since there is patent in it formed matter and materialized form and the property of composition itself.”[1448] The compound besides these three things has its own nature and so is represented by four. Now 1 + 2 + 3 + 4 = 10. “Wherefore every whole and perfect thing is ten.”
From mathematics to astronomy to astrology.
That Grosseteste’s “mathematics” includes astronomy is indicated by his citing “mathematicos” as explaining that the sun burns the regions under the tropic of capricorn more than those under the tropic of cancer, because an eccentric of the sun when it is in capricorn brings it closer to the earth.[1449] These mathematicians disagree on this point with the commentator upon Aristotle who believed that the sun burned more in Cancer. If for Grosseteste mathematics included astronomy, astronomy also included astrology—although he does not usually employ the word mathematicus for an astrologer. To his attitude toward astrology we now turn.
Astrology in natural philosophy, agriculture, alchemy, medicine and music.
Grosseteste accepts astronomy or astrology as the supreme science and says in his treatise on the liberal arts that natural philosophy needs its aid more than that of the others.[1450] There is scarcely any operation whether of nature or of man, such as the planting of vegetables, or transmutation of minerals, or cure of diseases, which can dispense with astronomical assistance. For inferior nature does not act except as celestial virtue moves and directs it. He then goes on to detail the effects of the moon, Saturn, and Mars on the hour of planting, and then to emphasize the importance of selecting the favorable hours astrologically in medical practice and in alchemy where he associates the seven planets with seven metals.[1451] He also argues that the harmony of the movements of the celestial spheres is found also in their effects upon the inferior world.[1452] Therefore he who knows the due proportion of the elements in the human body and the concord of the soul with the body, can restore any lack of harmony in the same to its proper state.[1453] In other words, diseases and even wounds and deafness should be curable by music based upon a knowledge of astrology and mathematics, and one should also be able to control such emotions as joy, grief, and wrath.
Some astrological technical detail.
In another treatise on how to predict the weather (De impressionibus aeris seu de prognosticatione[1454]) Grosseteste says that one must know such things as the powers of the signs and the natures of the planets.[1455] He then relates the four elements and four qualities to the planets and signs and proceeds to such further technical astrological terms as house, exaltation, triplicitas, terminus, facies, and aspect, and to an explanation of the effect of the eccentrics of the sun and moon upon inferior objects.[1456]
Man and the stars.
Grosseteste, like most of our Christian authors, exempts man in part by virtue of his free will and rational soul from the control of the stars. One of his brief fragments is entitled “That man is a microcosm” (Quod homo sit minor mundus), that is, a replica of the surrounding universe.[1457] One of his arguments for the finiteness of this world and of the stars is that all things are made for man and that when he no longer requires the processes of generation and corruption which the movements of the heavens cause, the heaven itself will cease to move and time will be no more.[1458] In a treatise on freedom of the will, he follows Augustine in The City of God in affirming that the rational soul is sublimer than the stars and in denying that all our actions which seem to be freely willed by us are predictable from the constellations, and that fate prevails as a necessity in all inferiors from the motion of the stars. He admits, however, that the human body is subject to two forces; as part of the world of cause it is changed in many ways by the movements of the stars, but it also is subject to the control of the mind especially in voluntary actions.
Grosseteste’s theory of comets.
Grosseteste has an ingenious theory which I do not remember having met elsewhere to explain why comets are signs of great disasters. In his treatise on comets he states that a comet is sublimated fire which has been separated from terrestrial nature and assimilated to celestial nature.[1459] The cause of this separation and assimilation by which comets are generated is the virtue of the heavenly bodies. Moreover, each comet has a particular star of its own which draws it as iron is drawn by adamant. This star, even if it is one of the fixed stars, must be related to one of the planets and hence the comet is under some planet also. Grosseteste then further explains that in every earthly object there are incorporated through the action of the celestial bodies particles of a more spiritual sort assimilated to the celestial natures. The generation of a comet, a process in which these fiery or ethereal particles are released from matter and carried up on high, is therefore the first step and sign of a more general release of the spiritual nature and of the consequent corruption of the terrestrial objects and compounds concerned, namely: in the first place, those under the rule of the same planet as the comet in question, and, in the second place, those in the region from which the comet was sublimated.[1460] But it is not easy to discern over which region the comet has especial significance of all those regions which are under the same parallel in which it appears, unless, concludes Grosseteste naïvely, it is that region where men are most alarmed by it.
Alchemy.
Grosseteste makes one or two incidental allusions to alchemy which show that he was a believer in the possibility of transmuting metals. He avers that nature intended that all metals should be gold, and that they vary from it only by degrees of imperfection.[1461] In another passage[1462] he mentions a theory of “the doctors of alchemy” that in each natural object there is, besides the four elements composing it, a fifth essence, unchangeable in itself but alterable after it has descended into inferior bodies. Here again we find a connection between alchemy and astrology.
Other treatises.
It is probable that not all of Grosseteste’s astrological writings are included in Baur’s edition. He mentions but does not publish a Digby manuscript and another of the thirteenth century in the Bibliothèque Nationale. Both are astronomical or astrological.[1463] A fourteenth century manuscript in the British Museum contains a treatise of “Grosthede” on the medicinal virtues of herbs.[1464] After the name of each herb the word “Grosthede” is usually added as if the items were extracts from a larger work. The treatise is not included in Baur’s edition and is perhaps spurious.
Summa philosophiae ascribed to Grosseteste.
Baur includes in his edition of Grosseteste’s philosophical works a Summa philosophiae which is longer than the other scientific treatises put together but which is probably spurious. The latest authors whom it cites are Alexander of Hales who died before Grosseteste and Albertus Magnus who possibly had written many of his works and made his reputation before 1253 although he lived on until 1280. Its several mentions of Albert are much more likely, however, to have been penned by some younger man than Grosseteste.[1465] And unless a passage referring to the death of Simon de Montfort after the appearance of a comet in 1264[1466] is an interpolation, the Summa cannot be by Grosseteste, unless in the sense that it represents his teaching or is an incomplete work of his to which someone else later put the finishing touches.
Its contents.
The Summa is, like the encyclopedias of Bartholomew of England and Thomas of Cantimpré, in nineteen books,[1467] a number perhaps chosen in deference to the seven planets and twelve signs of the zodiac. These books are devoted to the following topics: 1. the rise of philosophy; 2. truth; 3. science; 4. matter; 5. form; 6. virtue; 7. the first cause; 8. the universe—one but not eternal; 9. bodies, space, and vacuum; 10. intelligence and intelligences; 11. the rational soul; 12. the sensitive soul; 13. the vegetative soul; 14. light; 15. the sphere or heavens; 16. nature, universal and particular, and natural virtue; 17. elements and compounds; 18. meteorology; 19. minerals and metals.[1468]
Oriental origin of philosophy.
The account of the rise of philosophy includes considerable mention of occult sciences, with which it would seem to have been closely associated from the first.[1469] The Chaldeans are called the first famous philosophers. Sem is regarded as the founder of astrology and Cham, whom some identify with Zoroaster, is said to have invented the seven liberal arts. Abraham’s instruction of the Egyptians in astrology and arithmetic is next mentioned and then Atlas and his nephew Mercury, and the latter’s grandson Trismegistus, of the same name, are spoken of. This second Mercurius Trismegistus was according to Albumasar an illustrious astrologer, pre-eminent in theology and alchemy and magic and a famous prophet, but according to Augustine he was very worthless (vanissimus) in many respects. Long after this Homer revealed philosophy in his stories and Solomon philosophized concerning the nature of vegetables and animals, but in parables, it is believed.
Greek men of learning.
After mention of Abrachys, the astrologer of King Nebuchadnezzar, the author then lists the Greek philosophers from Thales to Socrates.[1470] The first philosopher in Italy was Pythagoras who had been thoroughly instructed in the science of the stars and magic by the Persians, Chaldeans and Egyptians. In less than a page a good estimate and contrast of Plato and Aristotle is made,[1471] and the author tries to explain why until the time of Arabic culture Plato was almost universally preferred to Aristotle among the Greeks and Latins. There follows a list of the learned Greeks: Empedocles, Heraclitus, Hippocrates, Euclid, Archimedes, and various orators, astronomers, astrologers, and naturalists (naturales) concluding with “Callisthenes the famous alchemist.”[1472]
Arabs and medieval Christians.
Among the Arabs three groups are distinguished of philosophers, mathematici or astrologers—among whom we are amazed to find Julius Firmicus listed, and medical writers.[1473] Thebit also is classed with the Arabs, but Plato of Tivoli, Costa ben Luca, Algazel, Gundissalinus, Constantinus, Theophilus Macer, and Philaretus are distinguished as Christian, and both Rabbi Moses as Hebrews.
Ancient and modern science compared.
Approaching his own time the author says that there are many other men whose excellent works of philosophy he has inspected but of whose names he is ignorant or has his reasons for keeping silent about.[1474] He does, however, name John the Peripatetic and Alfred, and still more recently Alexander the Minorite and Albert of Cologne, the friar preacher, as eminent philosophers and yet not to be considered authorities. The author nevertheless has no uncritical veneration for the learned men of the past. He thinks that with the exception of the Peripatetics very few of them had a complete or correct knowledge of the principles of nature and causes of natural phenomena or concerning the transmutation of the elements and the composition of physical bodies.[1475] Compared with moderns he finds their comprehension slight, except as they had fewer problems to occupy them and got results by concentrating for a long time on these. But he can think of no one among them except Boethius who was not guilty of some erroneous opinion. This attitude, however, is perhaps more owing to Christian prejudice than scientific superiority on our author’s part.
Criticism of Aristotle and the Arabic text.
Even Aristotle does not escape criticism. We are told that we should not accept his statement concerning the number of movers of the heavenly spheres, for, as Avicenna and Rabbi Moses have pointed out, the science of astronomy was little developed in his time.[1476] Nor are the Arabian commentators upon Aristotle left uncensured. It is said that some of the works of Aristotle in their present form smack more of Arabic loquacity than of Greek eloquence or the Aristotelian style, and that, especially in the Arabic text, interpolations and additions and alterations have been made involving patent anachronisms. Probably there have also been corresponding omissions.[1477] These criticisms of the Arabic text of Aristotle remind us of those which Roger Bacon said Grosseteste made.
Use of the word “modern.”
The author of this Summa is quite fond of employing the word “modern” which we heard him use above. He also tells how “Ptolemy, and other more modern mathematici” introduce epicycles in the orbits of the planets to save appearances, but have not fully determined “whether it is really so.”[1478] He also speaks of “Avenalpetras and the more modern Arabs” and calls Albertus Magnus “the most famous of the more modern theologians.”[1479]
Theology, philosophy, and science; speculative and experimental.
It is rather outside the limits of our investigation, but I cannot refrain from noting the Summa’s division of theologians into three classes: first, those who are original and have been made saints by the pope; second, those who are original and have not been sainted; third, the unoriginal minds who compile Summae from the works of the other two classes.[1480] The author believes that theology may utilize philosophy to refute heretics but that it must beware of making philosophy its chief end and should use theological terms as far as it can.[1481] Later he states that there are eight celestial spheres, according to the philosophers, nine according to the theologians who include the waters above the firmament as one.[1482] The author divides science into theoretical or speculative and practical or operative. He also has a touch of experimental science, asserting that very many experiences have proved that water will harden into stone,[1483] that the rules of genethlialogy and the predictions of astrologers are based upon the many specific cases observed and classified from experience by past astrologers,[1484] that many experiences in his own age—some of which he presently mentions—have shown that terrible events always follow the appearance of a comet,[1485] and that the alchemists had learned from many experiments that metals can be transmuted.
Astrology.
This favoring attitude toward astrology and alchemy is about all that there is left for us to notice in the Summa. The author thinks that no one has ever adequately treated the virtues appropriate to each planet, but quotes Rabbi Moses and Albumasar somewhat on this point.[1486] He has no difficulty in believing simultaneously in freedom of the will and genethlialogy.[1487] He also cites the passage in Albumasar concerning the astrological prediction of the virgin birth of Jesus Christ.[1488] In discussing comets, instead of attempting to explain their signifying disaster to whole regions naturally, as we heard Grosseteste do in his treatise on comets, the author of the Summa holds that “they appear of necessity by the will of God alone, not by chance or nature, but by the ministry of intelligences.”[1489] This was also the case with the star seen at Christ’s nativity. It may be, however, that this entire passage about comets and other astrological matters is an interpolation in the Summa, since it is in it that the mention of the date 1264 occurs to which we before alluded. The writer then goes on to say that his master, who was “most skilled in natural and mathematical science and most perfect in theology and most holy in life and religion,” taught him that Noah’s flood was necessitated by a constellation which God had foreordained for the wickedness of the then world.[1490] This, too, is perhaps a sign of an addition by some disciple of Grosseteste.
Occult virtue and alchemy.
The author of the Summa believes in occult virtue in nature and attributes it to the stars.[1491] He accepts Albertus Magnus’s explanation of the marvelous virtues of gems as due to celestial influence.[1492] He believes that metals are generated in the earth by the same force and are seven in number according to the seven planets, and thinks that this process can be simulated by alchemy.[1493] In discussing that subject Hermes is his chief authority. The Summa terminates by explaining the superiority of steel to iron and listing various salts.[1494]
Brother Giles on the comet of 1264.
Since we have mentioned the comet of 1264, we may note farther that it was the occasion of a treatise by Brother Giles of the Order of Dominicans, on the essence, motion, and signification of comets,[1495] in which he cites Grosseteste De iudiciis and alludes to the death of Pope Urban IV in that year. The comet was seen in the kingdom of France from mid-July to October and “stupefied the minds of many.”
[1421] References to Grosseteste’s works, unless otherwise stated, will be to Ludwig Baur, Die Philosophischen Werke des Robert Grosseteste, Münster, 1912, in Baeumker’s Beiträge zur Geschichte der Philosophie des Mittelalters, Vol. IX. This edition seems to make little effort to correct errors of case or number in the MSS, so that much of the text is far from being smooth reading. Baur discussed Die Philosophie des Robert Grosseteste in Vol. XVIII (1917) of the same series. The life of Grosseteste is treated briefly in DNB, and more fully in the old and pedantic work of Samuel Pegge, The Life of Robert Grosseteste, London, 1793, 385 quarto pages with many foot-notes and appendices, which however are based mainly on the works of preceding antiquaries, the author stating in his preface, “my private station as a country clergyman would not permit me to have much access to public libraries, but the materials were chiefly to be sought for in a book-room which, you will easily suppose, cannot be very richly or amply furnished.” Pegge’s Life was already described in 1861 as “one of the scarcest of modern works”; but the British Museum possesses two copies. Other biographies are by J. Felten, Freiburg, 1887, and F. Stevenson, London, 1889. The letters of Grosseteste, which do not especially concern us, are edited by H. R. Luard in RS XXV, 1861.
Not to be confused with Grosseteste is Robertus Anglicus who wrote a commentary on the Sphere of Sacrobosco in 1271, a Tractatus quadrantis at Montpellier in 1276 (printed 1508), and Canons for the Astrolabe (printed at Colle about 1478): see Duhem, III (1915), pp. 292, 298.
[1422] Brewer, 70 and 75.
[1423] Pegge (1793), p. 8, and Appendix II.
[1424] Brewer, 91; Bridges, I. 67.
[1425] Brewer, 472.
[1426] Baur, 49-50. If, on the other hand, the mention of an Arabic year indicates that the treatise is a translation of an Arabic work, the date would seem almost too late for Grosseteste to have effected the translation. It will be recalled that Bartholomew of England included “Robert of Lincoln” in his bibliography.
[1427] Pegge (1793), 267-91.
[1428] Wharton, Anglia Sacra, II, 325-41, de vita Grosteste auctore Richardo monacho Bordenienso. This life was apparently written about 1500.
[1429] Baur, 124.
[1430] Baur, 105.
[1431] Baur, 150.
[1432] Baur, 68.
[1433] Baur, 36.
[1434] In Sacro Bosco, Joannes de, Sphera, cum commentis, 1518, Reverendissimi Episcopi Roberti Lincolinensis Sphere Compendium, fol. 131 (B1). Baur, 13. De sphaera.
[1435] Baur, 25, De sphaera; Sacro Bosco, fol. 133 (F2).
[1436] De generatione stellarum, Baur, 33 and 34.
[1437] De natura locorum, Baur, 68.
[1438] De iride, seu de iride et speculo, Baur, 72-73.
[1439] Baur, 74.
[1440] Baur, 75.
[1441] Baur, 41.
[1442] In the Temple classics, vol. III, pp. 113-4.
[1443] Baur, 40.
[1444] Baur, 60.
[1445] See below, chapter 61, p. 644.
[1446] See the frequent citations of Grosseteste in his De Correctione Kalendarii, in an edition of the works of d’Ailly and Gerson printed about 1480.
[1447] On the general subject, Kaltenbrunner, Die Vorgeschichte der gregorianischen Kalendarreform, 1876.
[1448] De luce seu de inchoatione formarum, Baur, 58.
[1449] De natura locorum, Baur, 69.
[1450] De artibus liberalibus, Baur, 5.
[1451] Baur, 6-7.
[1452] Baur, 3.
[1453] Baur, 4-5.
[1454] Dover Priory, 409, fol. 80r, Pronostica Roberti Grosteste, would seem from its opening words, “Hoc ornamentum ...” to be the geomancy ascribed to various authors rather than this treatise by Grosseteste.
[1455] Baur, 42.
[1456] Baur, 44.
[1457] Baur, 59.
[1458] Baur, 106.
[1459] Baur, 38.
[1460] Baur, 39-40.
[1461] De artibus liberalibus, Baur, 6.
[1462] De generatione stellarum, Baur, 36.
[1463] Baur, 143.
[1464] Sloane 3468, fols. 43v-64r.
[1465] Baur, 280, 505, 633.
[1466] Following the passage in question, 587-88, other events mentioned are in the life of Emperor Frederick II and Louis IX’s departure from Aigues-Mortes to Egypt in 1248.
[1467] In Erh Ya, the earliest Chinese dictionary, the entries are arranged for ready reference under nineteen heads.
[1468] These headings are not given in the text but are made up by me to indicate its contents.
[1469] I, 1, (Baur, 275-77). For the origins of “mathematical science” see also XV, 12, (Baur, 561).
[1470] I, 2, (Baur, 277).
[1471] I, 3, (Baur, 278).
[1472] I, 4, (Baur, 278-79).
[1473] 1, 6, (Baur, 279).
[1474] Baur, 280.
[1475] I, 7, (Baur, 281).
[1476] X, 25, (Baur, 457).
[1477] I, 10, (Baur, 283): see too XV, 5, (Baur, 551).
[1478] XV, 14, (Baur, 565), Ptolemaeus etiam, ceterique moderniores mathematici: see also XV, 16, (Baur, 567), nonnullisque etiam modernioribus mathematicis.
[1479] XV, 5, (Baur, 551): XII, 17, (Baur, 505).
[1480] I, 11, (Baur, 284-85).
[1481] I, 13, (Baur, 288).
[1482] XV, 12, (Baur, 560).
[1483] XIX, 2, (Baur, 627).
[1484] XV, 30, (Baur, 588).
[1485] XV, 29, (Baur, 586).
[1486] XV, 28, Baur, 583. “De effectibus planetarum famossisimis et de eorum qualitatibus.”
[1487] XV, 30, (Baur, 588-89).
[1488] I, 9, (Baur, 282).
[1489] XV, 29, (Baur, 586).
[1490] Baur, 589.
[1491] XVI, 5, (Baur, 594).
[1492] XIX, 6, 7, (Baur, 633-34).
[1493] XIX, 8-9 and 13, (Baur, 635-36, and 641).
[1494] XIX, 13-14, (Baur, 641-3).
[1495] Pembroke 227, 14-15th century, fol. 250. “Inc. tract. fratris Egidii ordinis fratrum predicatorum de essencia motu et significacione cometarum. Quoniam multorum animos andivi stupefactos ... occasione ... stelle caudate ... que apparuit in regno francie ... a 19º kal. aug. usque 5º non. oct. a. d. 1264.” CUL 2022 (Kk. IV. 7) 15th century, fols. 91-96r. Fratris Egidii de cometis.