Principal works
کارهای اصلی

The Canon of Medicine

Avicenna authored a five-volume medical encyclopedia: The Canon of Medicine (Al-Qanun fi't-Tibb). It was used as the standard medical textbook in the Islamic world and Europe up to the 18th century. The Canon still plays an important role in Unani medicine.

Liber Primus Naturalium

Avicenna considered whether events like rare diseases or disorders have natural causes. He used the example of polydactyly to explain his perception that causal reasons exist for all medical events. This view of medical phenomena anticipated developments in the Enlightenment by seven centuries.

The Book of Healing

The Book of Healing (Arabic: کتاب الشفاء, romanized: Kitāb al-Shifāʾ; Latin: Sufficientia; also known as The Cure or Assepha) is a scientific and philosophical encyclopedia written by Abu Ali ibn Sīna (aka Avicenna) from medieval Persia, near Bukhara in Maverounnahr. He most likely began to compose the book in 1014, completed it around 1020, and published it in 1027. This work is Ibn Sina's major work on science and philosophy, and is intended to "cure" or "heal" ignorance of the soul. Thus, despite its title, it is not concerned with medicine, in contrast to Avicenna's earlier The Canon of Medicine (5 vols.) which is, in fact, medical. The book is divided into four parts: logic, natural sciences, mathematics (a quadrivium of arithmetic, geometry, astronomy), and metaphysics.It was influenced by ancient Greek philosophers such as Aristotle; Hellenistic thinkers such as Ptolemy; and earlier Persian/Muslim scientists and philosophers, such as Al-Kindi (Alkindus), Al-Farabi (Alfarabi), and Al-Bīrūnī.

The Book of Healing

Earth sciences

Avicenna wrote on Earth sciences such as geology in The Book of Healing. While discussing the formation of mountains, he explained:

Either they are the effects of upheavals of the crust of the earth, such as might occur during a violent earthquake, or they are the effect of water, which, cutting itself a new route, has denuded the valleys, the strata being of different kinds, some soft, some hard ... It would require a long period of time for all such changes to be accomplished, during which the mountains themselves might be somewhat diminished in size.

Philosophy of science

In the Al-Burhan (On Demonstration) section of The Book of Healing, Avicenna discussed the philosophy of science and described an early scientific method of inquiry. He discussed Aristotle's Posterior Analytics and significantly diverged from it on several points. Avicenna discussed the issue of a proper methodology for scientific inquiry and the question of "How does one acquire the first principles of a science?" He asked how a scientist would arrive at "the initial axioms or hypotheses of a deductive science without inferring them from some more basic premises?" He explained that the ideal situation is when one grasps that a "relation holds between the terms, which would allow for absolute, universal certainty". Avicenna then added two further methods for arriving at the first principles: the ancient Aristotelian method of induction (istiqra), and the method of examination and experimentation (tajriba). Avicenna criticized Aristotelian induction, arguing that "it does not lead to the absolute, universal, and certain premises that it purports to provide." In its place, he developed a "method of experimentation as a means for scientific inquiry."

Logic

An early formal system of temporal logic was studied by Avicenna. Although he did not develop a real theory of temporal propositions, he did study the relationship between temporalis and the implication. Avicenna's work was further developed by Najm al-Dīn al-Qazwīnī al-Kātibī and became the dominant system of Islamic logic until modern times. Avicennian logic also influenced several early European logicians such as Albertus Magnus and William of Ockham. Avicenna endorsed the law of non-contradiction proposed by Aristotle, that a fact could not be both true and false at the same time and in the same sense of the terminology used. He stated, "Anyone who denies the law of non-contradiction should be beaten and burned until he admits that to be beaten is not the same as not to be beaten, and to be burned is not the same as not to be burned."

Physics

In mechanics, Avicenna, in The Book of Healing, developed a theory of motion, in which he made a distinction between the inclination (tendency to motion) and force of a projectile, and concluded that motion was a result of an inclination (mayl) transferred to the projectile by the thrower, and that projectile motion in a vacuum would not cease. He viewed inclination as a permanent force whose effect is dissipated by external forces such as air resistance. The theory of motion presented by Avicenna was probably influenced by the 6th-century Alexandrian scholar John Philoponus. Avicenna's is a less sophisticated variant of the theory of impetus developed by Buridan in the 14th century. It is unclear if Buridan was influenced by Avicenna, or by Philoponus directly. In optics, Avicenna was among those who argued that light had a speed, observing that "if the perception of light is due to the emission of some sort of particles by a luminous source, the speed of light must be finite." He also provided a wrong explanation of the rainbow phenomenon. Carl Benjamin Boyer described Avicenna's ("Ibn Sīnā") theory on the rainbow as follows:

Independent observation had demonstrated to him that the bow is not formed in the dark cloud but rather in the very thin mist lying between the cloud and the sun or observer. The cloud, he thought, serves as the background of this thin substance, much as a quicksilver lining is placed upon the rear surface of the glass in a mirror. Ibn Sīnā would change the place not only of the bow, but also of the color formation, holding the iridescence to be merely a subjective sensation in the eye.

In 1253, a Latin text entitled Speculum Tripartitum stated the following regarding Avicenna's theory on heat:

Avicenna says in his book of heaven and earth, that heat is generated from motion in external things.

Psychology

Avicenna's legacy in classical psychology is primarily embodied in the Kitab al-nafs parts of his Kitab al-shifa (The Book of Healing) and Kitab al-najat (The Book of Deliverance). These were known in Latin under the title De Anima (treatises "on the soul").[dubious – discuss] Notably, Avicenna develops what is called the Flying Man argument in the Psychology of The Cure I.1.7 as defence of the argument that the soul is without quantitative extension, which has an affinity with Descartes's cogito argument (or what phenomenology designates as a form of an "epoche"). Avicenna's psychology requires that connection between the body and soul be strong enough to ensure the soul's individuation, but weak enough to allow for its immortality. Avicenna grounds his psychology on physiology, which means his account of the soul is one that deals almost entirely with the natural science of the body and its abilities of perception. Thus, the philosopher's connection between the soul and body is explained almost entirely by his understanding of perception; in this way, bodily perception interrelates with the immaterial human intellect. In sense perception, the perceiver senses the form of the object; first, by perceiving features of the object by our external senses. This sensory information is supplied to the internal senses, which merge all the pieces into a whole, unified conscious experience. This process of perception and abstraction is the nexus of the soul and body, for the material body may only perceive material objects, while the immaterial soul may only receive the immaterial, universal forms. The way the soul and body interact in the final abstraction of the universal from the concrete particular is the key to their relationship and interaction, which takes place in the physical body. The soul completes the action of intellection by accepting forms that have been abstracted from matter. This process requires a concrete particular (material) to be abstracted into the universal intelligible (immaterial). The material and immaterial interact through the Active Intellect, which is a "divine light" containing the intelligible forms. The Active Intellect reveals the universals concealed in material objects much like the sun makes colour available to our eyes.

Other contributions

Astronomy and astrology

Avicenna wrote an attack on astrology titled Resāla fī ebṭāl aḥkām al-nojūm, in which he cited passages from the Quran to dispute the power of astrology to foretell the future. He believed that each planet had some influence on the earth, but argued against astrologers being able to determine the exact effects. Avicenna's astronomical writings had some influence on later writers, although in general his work could be considered less developed than Alhazen or Al-Biruni. One important feature of his writing is that he considers mathematical astronomy as a separate discipline to astrology. He criticized Aristotle's view of the stars receiving their light from the Sun, stating that the stars are self-luminous, and believed that the planets are also self-luminous. He claimed to have observed Venus as a spot on the Sun. This is possible, as there was a transit on 24 May 1032, but Avicenna did not give the date of his observation, and modern scholars have questioned whether he could have observed the transit from his location at that time; he may have mistaken a sunspot for Venus. He used his transit observation to help establish that Venus was, at least sometimes, below the Sun in Ptolemaic cosmology, i.e. the sphere of Venus comes before the sphere of the Sun when moving out from the Earth in the prevailing geocentric model. He also wrote the Summary of the Almagest, (based on Ptolemy's Almagest), with an appended treatise "to bring that which is stated in the Almagest and what is understood from Natural Science into conformity". For example, Avicenna considers the motion of the solar apogee, which Ptolemy had taken to be fixed.

Chemistry

Avicenna was first to derive the attar of flowers from distillation and used steam distillation to produce essential oils such as rose essence, which he used as aromatherapeutic treatments for heart conditions.

Unlike al-Razi, Avicenna explicitly disputed the theory of the transmutation of substances commonly believed by alchemists:

Those of the chemical craft know well that no change can be effected in the different species of substances, though they can produce the appearance of such change.

Four works on alchemy attributed to Avicenna were translated into Latin as:

Liber Aboali Abincine de Anima in arte Alchemiae Declaratio Lapis physici Avicennae filio sui Aboali Avicennae de congelatione et conglutinatione lapidum Avicennae ad Hasan Regem epistola de Re recta

Liber Aboali Abincine de Anima in arte Alchemiae was the most influential, having influenced later medieval chemists and alchemists such as Vincent of Beauvais. However, Anawati argues (following Ruska) that the de Anima is a fake by a Spanish author. Similarly the Declaratio is believed not to be actually by Avicenna. The third work (The Book of Minerals) is agreed to be Avicenna's writing, adapted from the Kitab al-Shifa (Book of the Remedy). Avicenna classified minerals into stones, fusible substances, sulfurs and salts, building on the ideas of Aristotle and Jabir. The epistola de Re recta is somewhat less sceptical of alchemy; Anawati argues that it is by Avicenna, but written earlier in his career when he had not yet firmly decided that transmutation was impossible.

Poetry

Almost half of Avicenna's works are versified. His poems appear in both Arabic and Persian. As an example, Edward Granville Browne claims that the following Persian verses are incorrectly attributed to Omar Khayyám, and were originally written by Ibn Sīnā:

از قعر گل سیاه تا اوج زحل کردم همه مشکلات گیتی را حل بیرون جستم زقید هر مکر و حیل هر بند گشاده شد مگر بند اجل

From the depth of the black earth up to Saturn's apogee, All the problems of the universe have been solved by me. I have escaped from the coils of snares and deceits; I have unraveled all knots except the knot of Death.