The ''Book of Optics'' (; or ''Perspectiva''; ) is a seven-volume treatise on

optics Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of optical instruments, instruments that use or Photodetector, detect it. Optics usually describes t ...

and other fields of study composed by the medieval Arab scholar

Ibn al-Haytham Ḥasan Ibn al-Haytham (Latinization of names, Latinized as Alhazen; ; full name ; ) was a medieval Mathematics in medieval Islam, mathematician, Astronomy in the medieval Islamic world, astronomer, and Physics in the medieval Islamic world, p ...

, known in the West as Alhazen or Alhacen (965–c. 1040 AD). The ''Book of Optics'' presented experimentally founded arguments against the widely held extramission theory of vision (as held by

Euclid Euclid (; ; BC) was an ancient Greek mathematician active as a geometer and logician. Considered the "father of geometry", he is chiefly known for the '' Elements'' treatise, which established the foundations of geometry that largely domina ...

in his ''Optica''), and proposed the modern

intromission theory Visual perception is the ability to detect light and use it to form an image of the surrounding environment. Photodetection without image formation is classified as ''light sensing''. In most vertebrates, visual perception can be enabled by ph ...

, the now accepted model that vision takes place by light entering the eye.D. C. Lindberg (1976), ''Theories of Vision from al-Kindi to Kepler'', Chicago, Univ. of Chicago Press The book is also noted for its early use of the

scientific method The scientific method is an Empirical evidence, empirical method for acquiring knowledge that has been referred to while doing science since at least the 17th century. Historically, it was developed through the centuries from the ancient and ...

, its description of the

camera obscura A camera obscura (; ) is the natural phenomenon in which the rays of light passing through a aperture, small hole into a dark space form an image where they strike a surface, resulting in an inverted (upside down) and reversed (left to right) ...

, and its formulation of

Alhazen's problem Alhazen's problem is a mathematical problem in optics concerning reflection in a spherical mirror. It asks for the point in the mirror where one given point reflects to another. The special case of a concave spherical mirror is also known as ...

. The book extensively affected the development of optics,

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

and

mathematics Mathematics is a field of study that discovers and organizes methods, Mathematical theory, theories and theorems that are developed and Mathematical proof, proved for the needs of empirical sciences and mathematics itself. There are many ar ...

in Europe between the 13th and 17th centuries.

Vision theory

Before the ''Book of Optics'' was written, two theories of vision existed. The extramission or emission theory was forwarded by the mathematicians

and

Ptolemy Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzant ...

, who asserted that certain forms of radiation are emitted from the

eyes An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

onto the object which is being seen. When these

rays Ray or RAY may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), the bony or horny spine on ray-finned fish Science and mathematics * Half-line (geometry) or ray, half of a line split at an ...

reached the object they allowed the viewer to perceive its color, shape and size. An early version of the intromission theory, held by the followers of

Aristotle Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...

and

Galen Aelius Galenus or Claudius Galenus (; September 129 – AD), often Anglicization, anglicized as Galen () or Galen of Pergamon, was a Ancient Rome, Roman and Greeks, Greek physician, surgeon, and Philosophy, philosopher. Considered to be one o ...

, argued that sight was caused by agents, which were transmitted to the eyes from either the object or from its surroundings.

Al-Haytham Ḥasan Ibn al-Haytham ( Latinized as Alhazen; ; full name ; ) was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the princ ...

offered many reasons against the extramission theory, pointing to the fact that eyes can be damaged by looking directly at bright lights, such as the sun. He wrote of the low probability that the eye can fill the entirety of space as soon as the eyelids are opened as an observer looks up into the night sky. Using the intromission theory as a foundation, he formed his own theory that an object emits rays of light from every point on its surface which then travel in all directions, thereby allowing some light into a viewer's eyes. According to this theory, the object being viewed is considered to be a compilation of an infinite number of points, from which rays of light are projected.

Light and color theory

In the ''Book of Optics'', al-Haytham hypothesized the existence of primary and secondary light, with primary light being the stronger or more intense of the two. The book describes how the essential form of light comes from self-luminous bodies and that accidental light comes from objects that obtain and emit light from those self-luminous bodies. According to Ibn al-Haytham, primary light comes from self-luminous bodies and secondary light is the light that comes from accidental objects. Accidental light can only exist if there is a source of primary light. Both primary and secondary light travel in straight lines. Transparency is a characteristic of a body that can transmit light through them, such as air and water, although no body can completely transmit light or be entirely transparent. Opaque objects are those through which light cannot pass through directly, although there are degrees of opaqueness which determine how much light can actually pass through. Opaque objects are struck with light and can become luminous bodies themselves which radiate secondary light. Light can be refracted by going through partially transparent objects and can also be reflected by striking smooth objects such as mirrors, traveling in straight lines in both cases. Al-Haytham presented many experiments in ''Optics'' that upheld his theories about light and its transmission. He also wrote that color acts much like light, being a distinct quality of a form and travelling from every point on an object in straight lines. Through experimentation he concluded that color cannot exist without air.

Anatomy of the eye and visual process

As objects radiate light in straight lines in all directions, the eye must also be hit with this light over its outer surface. This idea presented a problem for al-Haytham and his predecessors, as if this was the case, the rays received by the eye from every point on the object would cause a blurred image. Al-Haytham solved this problem using his theory of refraction. He argued that although the object sends an infinite number of rays of light to the eye, only one of these lines falls on the eye perpendicularly: the other rays meet the eye at angles that are not perpendicular. According to al-Haytham, this causes them to be refracted and weakened. He believed that all the rays other than the one that hits the eye perpendicularly are not involved in vision. In al-Haytham's structure of the eye, the crystalline humor is the part that receives light rays from the object and forms a visual cone, with the object being perceived as the base of the cone and the center of the crystalline humor in the eye as the vertex. Other parts of the eye are the aqueous humor in front of the crystalline humor and the vitreous humor at the back. These, however, do not play as critical of a role in vision as the crystalline humor. The crystalline humor transmits the image it perceives to the brain through an optic nerve.

Volumes

* Book I deals with al-Haytham's theories on light, colors, and vision. * Book II is where al-Haytham presents his theory of visual perception. * Book III and Book IV present al-Haytham's ideas on the errors in visual perception with Book VI focusing on errors related to reflection. * Book V and Book VI provide experimental evidence for al-Haytham's theories on reflection. * Book VII deals with the concept of refraction.

Influence

The ''Book of Optics'' was most strongly influenced by Ptolemy's ''Optics'', while the description of the anatomy and physiology of the eye was based upon an account by Galen. The ''Book of Optics'' was translated into Latin by an unknown scholar at the end of the 12th (or the beginning of the 13th) century. The work was influential during the

Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of global history. It began with the fall of the Western Roman Empire and ...

.David Lindberg, Mark Smith and

Nader El-Bizri Nader El-Bizri (, ''nādir al-bizrĩ'') served as the dean of the College of Arts, Humanities, and Social Sciences at the University of Sharjah. He is currently a Senior Research Fellow at The Warburg Institute at the School of Advanced Study ...

note

Alhazen Ḥasan Ibn al-Haytham ( Latinized as Alhazen; ; full name ; ) was a medieval mathematician, astronomer, and physicist of the Islamic Golden Age from present-day Iraq.For the description of his main fields, see e.g. ("He is one of the princ ...

's considerable influence on the Perspectivists:
Smith, A. Mark (1981), "Getting the Big Picture in Perspectivist Optics" ''Isis'' 72(4) (Dec., 1981).
* *

, 'Seeing Reality in Perspective: The Art of Optics and the Science of Painting', in The Art of Science: From Perspective Drawing to Quantum Randomness, eds. Rossella Lupacchini and Annarita Angelini (Doredrecht: Springer, 2014), pp. 25–47.
Lindberg, David (1971) "Lines of Influence in Thirteenth-Century Optics: Bacon, Witelo, and Pecham" ''Speculum'' 46(1) (Jan., 1971), pp. 66–83
It was printed by

Friedrich Risner Friedrich Risner (Latin: Fridericus Risnerus; c.1533 – 15 September 1580) was a German mathematician from Hersfeld, Hesse. He was an assistant to Petrus Ramus (from around 1565) and was the first chair of mathematics at Collège Royale ...

in 1572, as part of his collection ''Opticae thesaurus''. This included a book on twilight falsely attributed to Alhazen, as well as a work on optics by

Vitello Vitello (; ; – 1280/1314) was a Polish friar, theologian, natural philosopher and an important figure in the history of philosophy in Poland. Name Vitello's name varies with some sources. In earlier publications he was quoted as Erazmus Ciol ...

English translations

* * * *
Books I–III (2001 – 91(4)) Vol. 1 Commentary and Latin text

– 91(5) Vol 2 English translation, Book I: TOC pp. 339–341, Book II: TOC pp. 415–416, Book III: TOC pp. 559–60, Notes 681ff, Bibl.
* 2 vols: . (

Philadelphia Philadelphia ( ), colloquially referred to as Philly, is the List of municipalities in Pennsylvania, most populous city in the U.S. state of Pennsylvania and the List of United States cities by population, sixth-most populous city in the Unit ...

American Philosophical Society The American Philosophical Society (APS) is an American scholarly organization and learned society founded in 1743 in Philadelphia that promotes knowledge in the humanities and natural sciences through research, professional meetings, publicat ...

), 2006 –
95(#2) Books 4–5 Vol. 1 Commentary and Latin text95(#3) Vol. 2 English translation, Notes, Bibl.
* Smith, A. Mark, ed. and trans. (2008) ''Alhacen on Image-formation and distortion in mirrors'' : a critical edition, with English translation and commentary, of Book 6 of Alhacen's ''De aspectibus'', he Medieval Latin version of Ibn al-Haytham's ''Kitāb al-Manāzir'' ''Transactions of the American Philosophical Society'', 2 vols: Vol. 1 98(#1, section 1 – Vol. 1 Commentary and Latin text); 98(#1, section 2 – Vol. 2 English translation). (

), 2008
Book 6 (2008) Vol. 1 Commentary and Latin textVol. 2 English translation, Notes, Bibl.
* Smith, A. Mark, ed. and trans. (2010) ''Alhacen on Refraction'' : a critical edition, with English translation and commentary, of Book 7 of Alhacen's ''De aspectibus'', he Medieval Latin version of Ibn al-Haytham's ''Kitāb al-Manāzir'' ''Transactions of the American Philosophical Society'', 2 vols: 100(#3, section 1 – Vol. 1, Introduction and Latin text); 100(#3, section 2 – Vol. 2 English translation). (

), 2010.
Book 7 (2010) Vol. 1 Commentary and Latin textVol. 2 English translation, Notes, Bibl.

References

Notes

Citations

{{Islamic mathematics 1010s books 1020s books 11th-century Arabic-language books 11th century in science Historical physics publications Physics books History of optics Optics, Book of Ibn al-Haytham