The Golden Age of Islam: Glimpses of Scientific Discovery and Invention (Cairo – Sicily)


This article gives glimpses of scientific discoveries and inventions by scientists in Cairo and Sicily during the Golden Age of Islam.

Cairo In the Eye of the Beholder

Abu Ali al-Hasan ibn al-Hasan ibn al-Haytham (c. 965-1039), known in the West as Alhazen, was the first person to test hypotheses with verifiable experiments, developing the scientific method more than 200 years before European scholars learned of it—by reading his books.

Ibn al-Haytham was the first person to apply algebra to geometry, founding the branch of mathematics known as analytic geometry. He seems to have written around 92 works of which, remarkably, over 55 have survived. The main topics on which he wrote were optics, including a theory of light and a theory of vision, astronomy, and mathematics; including geometry and number theory.

A seven-volume work on optics, Kitâb al-Manâdhir (Book of Optics), is considered by many to be his most important contribution. The previous major work on optics had been Ptolemy's Almagest. In Book I, Ibn al-Haytham makes it clear that his investigation of light will be based on experimental evidence rather than on abstract theory. He notes that light is the same irrespective of the source and gives the first correct explanation of vision, showing that light is reflected from an object into the eye.

His studies of optics led him to test his hypothesis that "lights and colors do not blend in the air," devising the world's first camera obscura, observed what happened when light rays intersected at its aperture, and recorded the results. Book II discusses visual perception, while Book III examines conditions necessary for good vision and how errors in vision are caused. Book IV is one of the most important as it discusses the theory of reflection; in Book V, he considers cylindrical and conical mirrors. Book VI of the Optics examines errors in vision due to reflection while the final book, Book VII, examines refraction.

A Modern Zij in Cairo

Abul-Hasan Ali Ibn Abd Al-Rahman Ibn Ahmad Ibn Yunus Al‑Sadafi (c. 950-1009), witnessed the Fatimid conquest of Egypt and the foundation of Cairo in 969. He served two Caliphs of the dynasty, making astronomical observations for them between 977 and 1003.

Ibn Yunus' importance in the history of astronomy stems mainly from his work, al-Zij al-Hakimi al-Kabir (a zij is an astronomical handbook with tables), which is a particularly fine example of this class of astronomical handbooks. This work is distinguished from other surviving Zijes in that it begins with a list of observations, made by both Ibn Yunus and some of his predecessors. In many respects his astronomical works have a modern appearance; many of the parameters which he used in his Zij are much superior to those of his predecessors and he is also known for his meticulous calculations and attention to detail.

Sicily: The delight of him who desires to journey through the climates

Abu Abdullah Muhammad Ibn Muhammad Ibn Abdullah Ibn Idris al‑Qurtubi al‑Hasani (1099-1166), was born in Ceuta, Spain, and educated in Cordova. He travelled far and wide for his studies, ending up at the Norman court in Palermo. His major contribution lies in medicinal plants as presented in his several books, especially Kitab al-Jami-li-Sifat Ashtat al-Nabatat. He studied and reviewed all literature on the subject of medicinal plants, collecting plants and data not reported earlier and adding them to botany, with special reference to medicinal plants.

Moreover, he made original contributions to geography, especially as related to economics, physical factors and cultural aspects. He described the world in Al‑Kitab al-Rujari, also entitled Nuzhat al-Mushtaq fi Ikhtiraq al-Afaq (The delight of him who desires to journey through the climates); practically a geographical encyclopedia of the time, containing information on Asia, Africa and Western countries. Al-Idrisi, later on, also compiled another geographical encyclopedia, larger than the former entitled Rawd-Unnas wa-Nuzhat al-Nafs (Pleasure of men and delight of souls).


Foundation for Science Technology and Civilization

1001 inventions: "Muslim Heritage in Our World" Book

This article was first published in print in the PSC Newsletter, 2nd School Semester 2010/2011.

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