After the languages, Bacon urged the pursuit of the sciences, which he conceived to be interdependent and corroborative; the conclusions of each of them susceptible of proof by the methods and data of the others.
“Next to languages,” says Bacon in chapter xxix. of the Opus tertium, “I hold mathematics necessary in the second place, to the end that we may know what may be known. It is not planted in us by nature, yet is closest to inborn knowledge, of all the sciences which we know through discovery and learning (inventionem et doctrinam). For its study is easier than all other sciences, and boys learn its branches readily. Besides, the laity can make diagrams, and calculate, and sing, and use musical instruments. All these are the opera of mathematics.”
Thus, with antique and mediaeval looseness, Bacon conceived this science. He devotes to it the long Pars quarta of the Opus majus: saying at the beginning that of—
“the four great sciences the gate and key is mathematics, which the saints found out (invenerunt) from the beginning of the world, and used more than all the other sciences. Its neglect for the past thirty or forty years has ruined the studies (studium) of the Latins. For whoso is ignorant of it cannot know the other sciences, nor the things of this world. But knowledge of this science prepares the mind and lifts it to the tested cognition (certificatam cognitionem) of all things.”
Bacon adduces authorities to prove the need of mathematics for the study of grammar and logic; he shows that its processes reach indubitable certitude of truth; and “if in other sciences we would reach certitude free from doubt, and truth without error, we must set the foundations of cognition in mathematics.”[641] He points out its obvious necessity in the study of the heavens, and in everything pertaining to speculative and practical astrologia; also for the study of physics and optics. Thus his interest lay chiefly in its application. As human science is nought unless it may be applied to things divine, mathematics must find its supreme usefulness in its application to the matters of theology. It should aid us in ascertaining the position of paradise and hell, and promote our knowledge of Scriptural geography, and more especially, sacred chronology. Next it affords us knowledge of the exact forms of things mentioned in Scripture, like the ark, the tabernacle, and the temple, so that from an accurate ascertainment of the literal sense, the true spiritual meaning may be deduced. It should not be confused with its evil namesake magic,[642] yet the true science is useful in determining the influence of the stars on the fortunes of states. Moreover, mathematics, through astrology, is of great importance in the certification of the faith, strengthening it against the sect of Antichrist;[643] then in the correction of the Church’s calendar; and finally, as all things and regions of the earth are affected by the heavens, astrology and mathematics are pertinent to a consideration of geography. And Bacon concludes Pars quarta with an elaborate description of the regions, countries, and cities of the known world.
Bacon likewise was profoundly interested in optics, the scientia perspectiva, which he sets forth elaborately in Pars quinta of the Opus majus. Much space would be needed to discuss his theories of light and vision, and the propagation of physical force, treated in the De multiplicatione specierum. He knew all that was to be learned from Greek and Arabic sources, and, unlike Albert, who compiled much of the same material, he used his knowledge to build with. Bacon had a genius for these sciences: his Scientia perspectiva is no mere compilation, and no work used by him presented either a theory of force or of vision, containing as many adumbrations of later theorizing.[644] Yet he fails to cast off his obsession with the “spiritual meaning” and the utility of science for theology. He discussed the composition of Adam’s body while in a state of innocence,[645] a point that may seem no more tangible than Thomas’s reasonings upon the movements of Angels, which Bacon ridicules. Again in his Optics, after an interesting discussion of refraction and reflection, he cannot forego a consideration of the spiritual significations of refracted rays.[646] Even his discussion of experimental science has touches of mediaevalism, which are peculiarly dissonant in this most original and “advanced” product of Bacon’s genius, which now must be considered more specifically.
The speculative intellect of the twelfth and thirteenth centuries was so widely absorbed with the matter and methods of the dominant scholasticism, that no one is likely to think of the eminent scholastics as isolated phenomena. Plainly they were but as the highest peaks which somewhat overtop the other mountains, through whose aggregation and support they were lifted to their supreme altitude. But with Bacon the danger is real lest he seem separate and unsupported; for the influences which helped to make him are not over-evident. Yet he did not make himself. The directing of his attention to linguistics is sufficiently accounted for by the influence of Grosseteste and others, who had inaugurated the study of Greek, and perhaps Hebrew at Oxford. As for physics or optics, others also were interested—or there would have been no translations of Greek and Arabic treatises for him to use;[647] and in mathematics there was a certain older contemporary, Jordanus Nemorarius (not to mention Leonardo Fibonacci), who far overtopped him. It is safe to assume that in the thirteenth, as in the twelfth and previous centuries, there were men who studied the phenomena of nature. But they have left scant record. A period is remembered by those features of its main accomplishment which are not superseded or obliterated by the further advance of later times. Nothing has obliterated the work of the scholastics for those who may still care for such reasonings; and Aquinas to-day holds sway in the Roman Catholic Church. On the other hand, the sparse footprints of the mediaeval men who essayed the paths of natural science have long since been trodden out by myriad feet passing far beyond them, along those ways. Yet there were these wayfarers, who made little stir in their own time, and have long been well forgotten. Had it not been for the letter from Pope Clement, Bacon himself might be among them; and only his writings keep from utter oblivion the name of an individual who, according to Bacon, carried the practice of “experimental science” further than he could hope to do. It may be fruitful to approach Bacon’s presentation of this science, or scientific method, through his references to this extraordinary Picard, named Peter of Maharncuria, or Maricourt.
In the Opus tertium, Bacon has been considering optics and mathematics, and has spoken of this Peter as proficient in them; and thus he opens chapter xiii., which is devoted to the scientia experimentalis:
“But beyond these sciences is one more perfect than all, which all serve, and which in a wonderful way certifies them all: this is called the experimental science, which neglects arguments, since they do not make certain, however strong they may be, unless at the same time there is present the experientia of the conclusion. Experimental science teaches experiri, that is, to test, by observation or experiment, the lofty conclusions of all sciences.” This science none but Master Peter knows.
By following the text further, we may be able to appreciate what Bacon will shortly say of him: