In the cultivation of the two sciences, geography was considered as dependent on history, and was often treated in connection with it and in a subordinate capacity. The Chaldean shepherds had already, upon the plains of Asia Minor, by the measurement of a degree of a great circle, determined the form and dimensions of the earth; their observations had been confirmed by the experiments of the Khalif Al-Mamun; and these important data were carried into Spain with many other treasures of Oriental wisdom. The earth was whimsically divided into seven zones or climates, to correspond with the seven planets and the seven metals known to the Arabs, that number having with them, as with other branches of the Semitic race, a peculiar and mystic significance. With the Arab, however, the study of the earth was rather topographical than geometric; his measurements were confined to the estimated distances between important points; and his figures were approximately calculated according to the popular but unreliable conception of the length of a day’s journey, which was usually twenty-five miles on land and a hundred miles by sea. The geographer, in his description of the provinces of a country, devoted much space to the location of springs, wells, and rivulets, a consideration of more importance in the mind of the traveller whose antecedents were to be traced to the pathless and arid wastes of Arabia than were even the woody shores and unruffled harbors of an hospitable coast to the eye of the shipwrecked mariner.
Nor must the libraries be omitted from this list of those factors of progress which so signally contributed to public enlightenment and to the formation of national character. There was no city of importance without at least one of these treasure-houses of literature. Their shelves were open to every applicant. Catalogues facilitated the examination of the collections and the classification of the various subjects. Many of the volumes were enriched with illuminations of wonderful beauty; the more precious were bound in embossed leather and fragrant woods; some were inlaid with gold and silver. Here were to be found all the learning of the past and all the discoveries of the present age,—the philosophy of Athens, the astronomy of Babylon, the science of Alexandria, the results of prolonged observation and experiment on the towers and in the laboratories of Cordova and Seville. Here also were mysterious treatises of Indian lore, whose origin ascended beyond the records of history, whose doctrines, perused for centuries in a dead language, had travelled through the medium of Greek and Arabic versions from the Indus to the Guadalquivir, and were ultimately destined to form the basis of the pantheistic ideas popular among educated persons at the present day. These opinions had, long anterior to the invasion of Tarik, provoked the curiosity and engaged the attention of studious Mohammedans. Under the khalifate, and subsequently, they were taught in the schools of the Peninsula, figured in elaborate disquisitions of philosophers, formed the subject of learned discussion in lyceums and literary assemblies. Their vital principles were founded upon the eternity of matter, the unity of intellect, the final absorption of the spirit of the individual into the Soul of the World. They accounted for the succession of natural phenomena by laws resulting from inevitable necessity. They refused to acknowledge the possibility of the supernatural, and renounced the time-honored and popular idea of incessant providential interventions. They ridiculed the apparitions of angels and demons as phantasms evoked by the credulity and fears of the ignorant. The tenets and ceremonial of religion were regarded as the convenient pretexts and apparatus of imposture. The origin of life was explained by the development of the germ through its latent force. The law of progressive evolution was considered susceptible of universal application, as embracing animal, vegetable, even mineral, forms. The theory of Lord Monboddo, promulgated in the eighteenth century and elaborated with such ingenuity by Darwin in our own time, was, it is evident, far from being original with either; for Moorish philosophers had, ages before, elucidated its leading principles. Thus, in the end, they even went to the extent of including in its operations every description of matter,—a course of thought evidently suggested by advanced Hindu conceptions and confirmed by the fancied analogy between the transmutation of metals and the transmigration of souls, doctrines also imported from the extreme Orient. These ideas, so antagonistic to the dogmas of religion, while long entertained in secret, had been first publicly advocated by Solomon-ben-Gabirol, the Jewish philosopher of Malaga, during the eleventh century. The Moorish school of rationalism soon included many distinguished names. The development of the mental faculties of humanity was declared to be a manifestation of the incessant activity of the omnipotent, intellectual principle that pervaded all Nature. The supreme object of human existence was the mastery of the sensations by the purer and nobler parts of the soul.
From these speculations, generally accepted, the opinions of many of the Hispano-Arab philosophers in time exhibited wide and radical divergence. Some, it is true, adhered to Peripatetic Pantheism in its integrity. Others oscillated between the extremes of mysticism and materialism. Against all, without exception, the doctors and the populace displayed a mortal hatred, whose influence even royal favor was not always able to withstand. Those who had risen to political eminence were compelled to relinquish their employments. Many were driven into exile. The intensity of popular odium forced those who still pursued their studies into obscurity, sometimes into penury. Consciousness of a defective title to the crown often impelled a prince to resort to the ignoble expedient of persecuting science for the sake of obtaining popularity. It was thus that Al-Mansur, the greatest of Moorish conquerors, himself an enthusiast for and an adept in the very studies he professed to condemn, as a political measure for the consolidation of his power discouraged literature and oppressed philosophy.
In spite of the extraordinary literary privileges within their grasp, the masses of Moorish Spain—largely dominated by African influence—never advanced beyond the primary stage of learning. It is true that they appreciated, in a measure, the benefits accruing from the employment of scientific methods in their various occupations of a mechanical or agricultural character. But this reluctant acknowledgment of the advantages of science extended no further. The invincible prejudices of the Semitic race clung to them through all the phases of their civilization. They never discarded the opinions born of a pastoral life, of all the most conducive to the perpetuation of ignorance. Their antipathy to innovation was only exceeded by the aversion they entertained towards all who questioned the authenticity of their religious belief. Greek philosophy they regarded with undisguised detestation. For their countrymen who devoted themselves to its study they evinced an abhorrence greater even than that with which they regarded apostasy.
The most famous of the natural philosophers of Mohammedan Spain, whose transcendent ability has caused him to be considered the exemplar of all, was Ibn-Roschid, popularly known as Averroes. His life embraced the greater portion of the twelfth century; his voluminous works on theology, jurisprudence, philosophy, and medicine denote an important epoch in Arabic literature; and his influence, which preponderated over that of any writer of his age, has survived the overthrow of his government, the dispersion of his people, the abandonment of his language, and the manifold catastrophes of more than seven hundred years. His industry was indefatigable. It is said that during the greater part of his life there were but two nights which he did not pass in study,—the night of his marriage and that of the death of his father. The genius he displayed in other professions has been overshadowed by the reputation he acquired as a philosopher. He occupied the responsible position of first physician to the Almohade Emir, Yakub-Al-Mansur-Billah. He administered for a time the office of Grand Kadi of Cordova. His immense erudition was the wonder of Europe. His commentaries on Aristotle were more highly esteemed by his disciples and admirers than were even the originals, the masterpieces of the great founder of the Peripatetics. His popularity with the Jews was so great that manuscripts of his works are more numerous in Hebrew than any other book except the Pentateuch. By his Mussulman contemporaries he was believed to have concluded a compact with Satan; to Christian theologians his name has ever been a synonym of evil. The audacity of his opinions was indeed calculated to provoke ecclesiastical indignation. He diligently inculcated the Indian dogma of Emanation and Absorption. He treated all revelations as impostures. Religions he pronounced convenient instruments of statecraft, admirable contrivances for the preservation of order and the encouragement of morality. The three then predominant in the world he held in equal contempt,—the Christian he declared was impossible; the Jewish he characterized as a creed adapted only to children; the Mohammedan as a doctrine for swine. He indulged in sarcasms highly derogatory to the sanctity of the Eucharist. His popularity among the clerical profession was not enhanced by the saying attributed to him: “The tyrant is he who governs for himself and not for the people, and the worst of tyrannies is that of the priest.”
The power of public opinion, stimulated by the efforts of orthodox Mussulmans, procured the disgrace of Averroes. He was deprived of his judicial office. The honorable post of court physician was taken from him. He was compelled to seek refuge in Africa; his property was confiscated; and, in age and infirmity, he was exposed to the insults of the fanatical rabble, who spat in his face as he sat helpless at the door of the mosque of Fez. With his death in 1198 disappeared from the Peninsula every outward trace of the doctrines of which he had been both the champion and the representative. Posterity, on account of the variety and excellence of his intellectual gifts, the extent of his erudition, and the boldness with which he asserted his opinions, has seen fit to dissociate him from the other learned men of his epoch, his instructors, his collaborators, his disciples. There were many other philosophers, however, such as Solomon-ben-Gabirol, Ibn-Badja, Ibn-Tofail, Ibn-Zohr, who were his equals in learning and scarcely inferior to him in natural courage and in argumentative ingenuity and eloquence.
The apparent extinction of his theories, obnoxious alike to muftis and populace, was illusory. Introduced with other branches of Moslem science by the Jews, through the convenient channels of France and Italy, they eventually permeated the intellectual life of Europe. The Universities of Paris and Padua, the literary centres of the age, were from the fourteenth to the sixteenth century foci of infidelity. The impiety of propositions openly promulgated by the faculties of those two great institutions would to-day shock any one except the most daring agnostic. The seed thus sown bore abundant fruit. All Italy became tainted with heresy. The Lateran Council, summoned to place the official stamp of ecclesiastical condemnation upon the prohibited doctrines, was unable to check their progress. The Jews carried these ideas everywhere; scholastics adopted them; they were even disseminated by members of the monastic orders. Alexander de Hales, of the Franciscans, was one of their ardent advocates. Robert Grossetête, Bishop of Lincoln, second in attainments and reputation only to his great contemporary Roger Bacon, believed in the Universal Intellect. It was Savonarola who wrote, “Ille ingenio divinus homo Averroes philosophus.” From the propagation of these theories was derived the idea of the mythical book, entitled De Tribus Impostoribus, an alleged satire aimed at Moses, Christ, and Mohammed, variously attributed to a score of authors; supposed to be filled with blasphemy; whose very title was a powerful weapon in the hands of the clergy, yet whose publication was apocryphal, and whose contents were necessarily purely imaginary.
The general acceptance and perpetuation of the opinions of Averroes, denounced from every pulpit, persecuted by the secular authority and anathematized by councils, is a striking proof of the universal decline of ecclesiastical power. The most popular poetical compositions bore the impress of the prevailing spirit of incredulity and pantheism, which indeed pervaded, to a greater or less extent, every class of literature. It was in vain that those most deeply concerned vehemently protested against the alarming growth of this detested heresy. No rank of the clerical order was exempt from its effects; it was whispered that its insidious influence had even penetrated the sacred precincts of the Vatican. That influence was transmitted unimpaired to posterity, and modern science is largely indebted for its inquisitive and impartial spirit to the doctrines of the great Arabian philosopher of the twelfth century.
In their treatment and application of the exact sciences, and especially in the development of the higher branches of mathematics, the Spanish Mohammedans exhibited pre-eminent ability. The Arabs were the first to ascertain with accuracy the length of the year. They tabulated the movements of the stars. They discovered the third lunar inequality of 45´ six hundred and fifty years before Tycho Brahe. They determined the eccentricity of the sun’s orbit; the movement of its apogee; the progressive diminution of the obliquity of the ecliptic; the amount of the precession of the equinoxes. To them is due the credit of having introduced to the knowledge of Europe many ingenious devices and processes of calculation which diminished labor, and, at the same time, opened new fields of investigation that otherwise might have remained unknown and unexplored. The grand work of Ptolemy, the Syntaxis, had, under the name of the Almagest, been translated before the ninth century, and been revised by Isaac-ben-Honein in 827. In the tenth century, the famous Abul-Wefa, of Bagdad, wrote an astronomical treatise to which he gave the same name, which caused the two to be long confounded by scholars. Both of these compositions, equally wonderful for their learning, were early known to the Spanish Arabs. The numerals of India, which they adopted, at once superseded the cumbersome Roman characters hitherto in use. The decimal system was also introduced by them. They greatly advanced the study of algebra, whose scope and possibilities had previously been imperfectly understood, and applied it to geometry. They substituted sines for chords, invented modern trigonometry, proposed a formula for the solution of cubic equations. They understood the principles of the calculus. Geber, of Seville, published rules for one of the most important demonstrations of spherical trigonometry. Al-Zarkal, of Toledo, was the first to suggest the substitution of the elliptical orbit to correct the errors of the generally accepted Ptolemaic system, thus anticipating Copernicus and Kepler. In his attempts to determine the movement of the sun’s apogee alone, he made four hundred and two observations; and the result he obtained was within a fraction of a second of the amount declared to be correct by modern astronomers. Abul-Hassan-Ali, by a series of observations extending over a distance of nine hundred leagues to establish the elevation of the pole, estimated with precision the dimensions of the Mediterranean. The catalogue made by Ibn-Sina contains a thousand and twenty-two stars. Ibn-Abi-Thalta studied the movements of the heavenly bodies without intermission for thirty years. Averroes, while computing the motion of the planet Mercury, discovered spots upon the sun. The far greater portion of the results of the labors of the Moorish astronomical observers of the Peninsula, having shared the general fate of the monuments of Moslem learning, are lost. No complete copy of the works of any Arab astronomer who lived since the ninth century is known to exist. The extent of this calamity may be inferred from the fact that in the royal library of Cairo there were six thousand works on mathematics, copies of many of which must have been in the hands of the Moslems of Spain, and none of which have survived. They made constant use of the formulas of Ibn-Junis for tangents and secants, of whose existence Europe was ignorant for six hundred years after their publication. As the duty of pilgrimage promoted the study of geography, so an acquaintance with astronomy was rendered necessary to Mohammedans by the requirements of their religion. In order to determine the direction of Mecca, an exact knowledge of the points of the compass was indispensable. It was equally important to establish, without error, the hours of prayer and of diurnal ablution, and the dates of festivals which began with the rising of the moon. These considerations, which invested astronomical pursuits with a semi-religious character, greatly promoted their popularity. The study of mathematics was, independently of this influence, an occupation especially congenial to the Arab mind. In all the schools were globes, both terrestrial and celestial, of wood and metal, planispheres, and astrolabes. The construction of these latter instruments, the precursors of the sextant, as perfected by the Arabs, was very complicated, and demanded the exercise of the highest degree of scientific ingenuity. They were used for the measurement of angles, and for ascertaining the hour either of the day or night. Some had as many as five tables, were engraved on both sides, and were provided at the bottom with eleven different projections for as many horizons. On them were represented the movement of the celestial sphere, the signs of the zodiac, and the position of the principal stars and constellations. Interchangeable plates, calculated for different latitudes, facilitated observations wherever made. It was not unusual for an astrolabe to give the latitudes of nearly a hundred cities. The invention of the pierced gnomon by Ibn-Junis greatly simplified observations made to determine the altitude of the sun. The passage of time was usually marked by sundials, and by clepsydras of complex and elaborate mechanism. The oscillatory property of suspended bodies, represented by the isochronism of the pendulum, was familiar to the Arabs, who had adapted it to a contrivance whose construction resembled that of the modern clock, an invention generally attributed to Galileo. Many of the instruments used by them in their astronomical observations were of enormous dimensions. Some of their armillary spheres were twenty-five feet in diameter, and quadrants with a radius of fifteen feet were not uncommon. The bronze sextant, employed in the tenth century for the determination of the obliquity of the ecliptic and described by Abul-Hassan, of Morocco, had a radius of fifty-eight feet, and its arc was divided into seconds. At that time astronomy, especially among the Spanish Moslems, had advanced as far as was possible without the use of the telescope. It was through the influence of the Arabs that knowledge of that science, as well as of all other branches of mathematics, was universally diffused. The modern almanac, as its name denotes, is their invention, and the signs by which it designates the seven planets have been transmitted through their agency. As with all pastoral nations, their attention was early directed to the phenomena of the heavens. They noted the rising and setting of certain stars which seemed intended to mark the advent of the seasons; they divided the most prominent groups into constellations, and assigned to them, as did the Greeks, a fanciful and legendary origin and nomenclature. With the practice of astral worship, incident to every race at a certain stage of its intellectual progress, was associated the study of astrology, whose principles, based upon the imaginary effect of benign or malignant planetary influence, has still in educated as well as in ignorant communities its enthusiastic votaries. The practice of this false but attractive science was, however, in no age confined to impostors. Some of the greatest minds of mediæval or modern times believed in its delusions, which were especially popular with the most eminent astronomers of the Middle Ages. Tycho Brahe, who gravely interpreted dreams, drew the horoscope of the Emperor Rudolph. Even the ability of Kepler did not preserve him from the prevalent superstition; he also cast horoscopes and published prophetic almanacs. Its pursuit led to the cultivation of other and more debased superstitions,—the chimerical follies of geomancy and oneiromancy, the profane rites of divination and magic, the belief in the occult virtues of talismans and amulets. The persistence of those practices, through unnumbered centuries to the present time, is a singular commentary on human credulity in enlightened as well as in unlettered ages. In many parts of Germany the horoscope of an infant is cast at its nativity, and is religiously preserved, with its baptismal certificate, until the hour of dissolution. Our farmers sow and reap and perform the various duties incident to rural economy with diligent attention to the phases of the moon. Confidence in the efficacy of talismans is even in our generation far from extinct. It is unconsciously manifested in the cruciform plan of our majestic cathedrals; in the gilded emblem which points heavenward on the summits of their loftiest towers; in the curves of their painted windows, glowing with all the hues of the rainbow; in the armorial bearings of some of the proudest royal houses of Europe; in the carvings of our furniture; in the horseshoe suspended over doorways; in the Teraphim and the phylacteries of the Jew; in the holy symbols embroidered upon the vestments of the Catholic clergy; in the badges of our secret societies; in the settings of the jewels which rise and fall on the voluptuous bosom of Beauty. The superstition of the evil-eye, universally prevalent in the Orient, is largely responsible for the employment of charms. It is not improbable that this belief may have been originally derived from the peculiar influence exercised by some person endowed with an extraordinary degree of hypnotic power. To animal magnetism—as a mysterious force—is certainly due a large proportion of the magic fascinations of ancient times; and the power of the serpent over birds and animals probably gave rise to the popular fable of the basilisk. The virtues of amulets were derived, according to common opinion, not from the substance of which they were composed, but from the portion of the Universal Intelligence by which they were supposed to be tenanted.
Thus a desire to penetrate the secrets of futurity and avert impending misfortune gave rise to the spurious science of astrology, itself the parent of astronomy. The European Arabs cultivated both with almost equal assiduity. The mind of the philosopher, disciplined by the daily habit of mathematical calculation, was yet unable to discard the delusions of the horoscope or to forget the visionary and fictitious properties of talismans. In the mental constitution of the ablest Arabian scholars, the fascination of the occult and the forbidden predominated over the experience of centuries, the influence of letters, and the dictates of reason.