The remaining ten or twelve years of Avicenna's life were spent in the service of Abu Ya‛far ‛Alā Addaula, whom he accompanied as physician and general literary and scientific adviser, even in his numerous campaigns. During these years he began to study literary matters and philology, instigated, it is asserted, by criticisms on his style. But amid his restless study Avicenna never forgot his love of enjoyment. Unusual bodily vigour enabled him to combine severe devotion to work with facile indulgence in sensual pleasures. His passion for wine and women was almost as well known as his learning. Versatile, light-hearted, boastful and pleasure-loving, he contrasts with the nobler and more intellectual character of Averroes. His bouts of pleasure gradually weakened his constitution; a severe colic, which seized him on the march of the army against Hamadān, was checked by remedies so violent that Avicenna could scarcely stand. On a similar occasion the disease returned; with difficulty he reached Hamadān, where, finding the disease gaining ground, he refused to keep up the regimen imposed, and resigned himself to his fate.

On his deathbed remorse seized him; he bestowed his goods on the poor, restored unjust gains, freed his slaves, and every third day till his death listened to the reading of the Koran. He died in June 1037, in his fifty-eighth year, and was buried in Hamadān.

It was mainly accident which determined that from the 12th to the 17th century Avicenna should be the guide of medical study in European universities, and eclipse the names of Rhazes, Ali ibn al-Abbas and Avenzoar. His work is not essentially different from that of his predecessors Rhazes and Ali; all present the doctrine of Galen, and through Galen the doctrine of Hippocrates, modified by the system of Aristotle. But the Canon of Avicenna is distinguished from the Al-Hawi (Continens) or Summary of Rhazes by its greater method, due perhaps to the logical studies of the former, and entitling him to his surname of Prince of the Physicians. The work has been variously appreciated in subsequent ages, some regarding it as a treasury of wisdom, and others, like Avenzoar, holding it useful only as waste paper. In modern times it has been more criticized than read. The vice of the book is excessive classification of bodily faculties, and over-subtlety in the discrimination of diseases. It includes five books; of which the first and second treat of physiology, pathology and hygiene, the third and fourth deal with the methods of treating disease, and the fifth describes the composition and preparation of remedies. This last part contains some contingent of personal observation.

He is, like all his countrymen, ample in the enumeration of symptoms, and is said to be inferior to Ali in practical medicine and surgery. He introduced into medical theory the four causes of the Peripatetic system. Of natural history and botany he pretends to no special knowledge. Up to the year 1650, or thereabouts, the Canon was still used as a text-book in the universities of Louvain and Montpellier.

About 100 treatises are ascribed to Avicenna. Some of them are tracts of a few pages, others are works extending through several volumes. The best-known amongst them, and that to which Avicenna owed his European reputation, is the Canon of Medicine; an Arabic edition of it appeared at Rome in 1593, and a Hebrew version at Naples in 1491. Of the Latin version there were about thirty editions, founded on the original translation by Gerard of Cremona. The 15th century has the honour of composing the great commentary on the text of the Canon, grouping around it all that theory had imagined, and all that practice had observed. Other medical works translated into Latin are the Medicamenta Cordialia, Canticum de Medicina, Tractatus de Syrupo Acetoso. Scarcely any member of the Arabian circle of the sciences, including theology, philology, mathematics, astronomy, physics and music, was left untouched by the treatises of Avicenna, many of which probably varied little, except in being commissioned by a different patron and having a different form or extent. He wrote at least one treatise on alchemy, but several others have been falsely attributed to him.

His book on animals was translated by Michael Scot. His Logic, Metaphysics, Physics, De Caelo, are treatises giving a synoptic view of Aristotelian doctrine. The Logic and Metaphysics have been printed more than once, the latter, e.g., at Venice in 1493, 1495 and 1546. Some of his shorter essays on medicine, logic, etc., take a poetical form (the poem on logic was published by Schmoelders in 1836). Two encyclopaedic treatises, dealing with philosophy, are often mentioned. The larger, Al-Shifā' (Sanatio), exists nearly complete in manuscript in the Bodleian library and elsewhere; part of it on the De Anima appeared at Pavia (1490) as the Liber Sextus Naturalium, and the long account of Avicenna's philosophy given by Shahrastani seems to be mainly an analysis, and in many places a reproduction, of the Al-Shifā', A shorter form of the work is known as the An-najāt (Liberatio). The Latin editions of part of these works have been modified by the corrections which the monkish editors confess that they applied.

There is also a Philosophia Orientalis, mentioned by Roger Bacon, and now lost, which according to Averroes was pantheistic in tone.

For Avicenna's life, see Ibn Khallikan's Biographical Dictionary, translated by McG. de Slane (1842); F. Wüstenfeld's Geschichte der arabischen Aerzte und Naturforscher (Göttingen, 1840). For his medicine, see Sprengel, Histoire de la Médecine; and for his philosophy, see Shahrastani, German trans. vol. ii. 213-332; K. Prantl, Geschichte der Logik, ii. 318-361; A. Stöckl, Phil. d. Mittelalters, ii. 23-58; S. Munk, Mélanges, 352-366; B. Haneberg in the Abhandlungen der philos.-philolog. Class. der bayerischen Academie (1867); and Carra de Vaux, Avicenne (Paris, 1900). For list of extant works see C. Brockelmann's Geschichte der arabischen Litteratur (Weimar, 1898), vol. i. pp. 452-458.

(W. W.; G. W. T.)