An article on the philosophy of light: what it is, how it spreads, and its laws

Al-Hasan ibn al-Haytham was the first to show that the theory of Euclid and others was wrong, that a ray of light emanates from the eye and falls on the thing seen. He determined the opposite of this theory, that the ray of light emerges from the thing seen and falls on the eye. He inferred from experience and observation that the extension of the light ray is on a line. straight. Ibn al-Haytham defined transparent bodies, which are those through which light penetrates and the sight can per...