The ''Book of Optics'' ( ar, كتاب المناظر, Kitāb al-Manāẓir; la, De Aspectibus or ''Perspectiva''; it, Deli Aspecti) 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 instruments that use or detect it. Optics usually describes the behaviour of visible, ultrav ...

and other fields of study composed by the medieval Arab scholar

Ibn 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 pri ...

, 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 (; grc-gre, Εὐκλείδης; 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 ...

in his ''Optica''), and proposed the modern intromission theory, 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 method for acquiring knowledge that has characterized the development of science since at least the 17th century (with notable practitioners in previous centuries; see the article history of scientific ...

, its description of the

camera obscura A camera obscura (; ) is a darkened room with a small hole or lens at one side through which an image is projected onto a wall or table opposite the hole. ''Camera obscura'' can also refer to analogous constructions such as a box or tent in w ...

, and its formulation of

Alhazen's problem Alhazen's problem, also known as Alhazen's billiard problem, is a mathematical problem in geometrical optics first formulated by Ptolemy in 150 AD. It is named for the 11th-century Arab mathematician Alhazen (''Ibn al-Haytham'') who presented a g ...

. The book extensively affected the development of optics,

physics Physics is the natural science that studies matter, its 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 which r ...

and mathematics 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 Emission theory, also called emitter theory or ballistic theory of light, was a competing theory for the special theory of relativity, explaining the results of the Michelson–Morley experiment of 1887. Emission theories obey the principle of rel ...

was forwarded by the mathematicians

and

Ptolemy Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance ...

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

eyes Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and con ...

onto the object which is being seen. When these

rays Ray may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), a bony or horny spine on a fin Science and mathematics * Ray (geometry), half of a line proceeding from an initial point * Ray (gra ...

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 (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...

and

Galen Aelius Galenus or Claudius Galenus ( el, Κλαύδιος Γαληνός; September 129 – c. AD 216), often Anglicized as Galen () or Galen of Pergamon, was a Greek physician, surgeon and philosopher in the Roman Empire. Considered to be one ...

, argued that sight was caused by agents, which were transmitted to the eyes from either the object or from its surroundings. Al-Haytham 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 claimed 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 claimed 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 claims about light and its transmission. He also claimed 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 claimed 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 VI present al-Haytham's ideas on the errors in visual perception with Book VI focusing on errors related to reflection. *Book IV and Book V 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 late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...

.David Lindberg, Mark Smith and

Nader El-Bizri Nader El-Bizri ( ar, نادر البزري, ''nādir al-bizrĩ'') is the Dean of the College of Arts, Humanities, and Social Sciences at the University of Sharjah. He served before as a tenured longstanding full Professor of philosophy and ci ...

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

, '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, via JSTOR
/ref> It was printed by

Friedrich Risner Friedrich Risner (c.1533 – 15 September 1580) (in Latin Fridericus Risnerus) 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 ( pl, Witelon; german: Witelo; – 1280/1314) was a 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 quo ...

English translations

* * * *
Books I-III (2001 — 91(4)) Vol 1 Commentary and Latin text via JSTOR

— 91(5) Vol 2 English translation, Book I:TOCpp.339-341, Book II:TOCpp.415-6, Book III:TOCpp.559-560, Notes 681ff, Bibl. via JSTOR
* 2 vols: . (

Philadelphia Philadelphia, often called Philly, is the List of municipalities in Pennsylvania#Municipalities, largest city in the Commonwealth (U.S. state), Commonwealth of Pennsylvania, the List of United States cities by population, sixth-largest city i ...

American Philosophical Society The American Philosophical Society (APS), founded in 1743 in Philadelphia, is a scholarly organization that promotes knowledge in the sciences and humanities through research, professional meetings, publications, library resources, and communit ...

), 2006 �
95(#2) Books 4-5 Vol 1 Commentary and Latin text via JSTOR95(#3) Vol 2 English translation, Notes, Bibl. via JSTOR
* 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'' He or HE may refer to: Language * He (pronoun), an English pronoun * He (kana), the romanization of the Japanese kana へ * He (letter), the fifth letter of many Semitic alphabets * He (Cyrillic), a letter of the Cyrillic script called ''He'' in ...

''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 text via JSTORVol 2 English translation, Notes, Bibl. via JSTOR
* 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'',

''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 text via JSTORVol 2 English translation, Notes, Bibl. via JSTOR

Notes

References

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