11. Ibn Sina achieved a far-reaching influence. His Canon of Medicine was highly esteemed even in the West, from the 13th century to the 16th, and it is still the authority for medical treatment among the Persians of the present day. On Christian Scholasticism his influence was important. [[148]]Dante placed him between Hippocrates and Galen; and Scaliger maintained that he was Galen’s equal in Medicine, and much his superior in Philosophy.
For the East he stood and yet stands as the Prince of Philosophy. In that region Neo-Platonic Aristotelianism continues to be known under the form which was given it by Ibn Sina. Manuscripts of his works abound,—an evidence of his popularity,—while commentaries on his writings, and epitomes of them, are countless. He was studied by physicians and statesmen, and even by theologians: It was only a few who went farther back and consulted his sources.
From the very first, of course, he had many enemies, and they were more noisy in their demonstrations than his friends. Poets cursed him: theologians either chimed in with him, or tried to refute him. And in Bagdad in the year 1150, the Caliph Mustandjid consigned to the flames Ibn Sina’s writings, as part of a certain judge’s philosophical library.
5. Ibn al-Haitham.
1. After the days of Ibn Sina and his school, little more attention was paid to the cultivation of Speculative Philosophy in the Eastern regions of the Muslim empire. In these lands Arabic was forced more and more to yield to Persian, both in life and in literature. That the Persian tongue is not so well adapted for abstract logical and metaphysical discussion—might be only of quite secondary importance, in connection with this decline in speculation; but the conditions of civilization, and with them the subjects which interested men, were sadly changed. [[149]]Ethics and Politics came more to the front, although without assuming an actually new form. But in the later Persian literature the predominant place was unmistakeably held by Poetry, partly of a free-thinking tendency, partly, and indeed preponderatingly, of a mystic kind, which satisfied the need for wisdom, experienced by people of culture.
From about the middle of the 10th century, the scientific movement which originated at Bagdad had in part turned westward. We have already found Farabi in Syria, and Masudi in Egypt: In the latter country Cairo was becoming a second Bagdad.
2. In Cairo, at the beginning of the 11th century, we come upon one of the most considerable mathematicians and physicists in all the Middle Ages, Abu Ali Mohammed ibn al-Hasan ibn al-Haitham (Alhazen). He had formerly been a government-official in Basra, his native town. Confiding too much in the practical value of his mathematical knowledge, he imagined that he could regulate the inundations of the Nile; but having been summoned on that account by the Caliph al-Hakim, he became aware, soon after his arrival, of the futility of his efforts. Thereupon he fell into disgrace as a public official, and went into hiding till the Caliph’s death, in 1021. From that time he devoted himself to literary and scientific work, up to his own death, in 1038.
His chief strength is shown in mathematics and its practical application; but he also devoted great attention to the writings of Galen and Aristotle, nor did he confine that attention to the physical treatises. By his own confession he had, in a spirit of doubt about everything, been [[150]]engaged, from his youth up, in considering the various views and doctrines of men, until he came to recognize in all of them more or less successful attempts to approximate to the truth. Moreover truth for him was only that which was presented as material for the faculties of sense-perception, and which received its form from the understanding, being thus the logically-elaborated perception. To seek such truth was his aim in the study of philosophy. In his view philosophy should be the basis of all the sciences. He found it in the writings of Aristotle, inasmuch as that sage had best understood how to knit sense-perception into a coherent whole with rational knowledge. With eagerness therefore he studied and illustrated Aristotle’s works, for the use and profit of mankind, as well as to exercise his own intellect and provide a treasure and consolation for his old age. Of these labours, however, nothing seems to have been preserved for us.
The most important of Ibn al-Haitham’s writings is the “Optics”, which has come down to us in a Latin translation and redaction. In it he shows himself to be an acute mathematical thinker, always taking pains with the analysis of hypotheses and of the actual examples. A Western, belonging to the 13th century (Vitello), was able to give a more methodical account of the whole subject; but yet in keenness of observation on specific points, Ibn al-Haitham may be reckoned his superior.