This is a much more complete work of Euclid than the Greek text that has come down to us. It was translated from the Greek by the famous philosopher and astronomer Khwājah Naṣīr al-Dīn al-Ṭūsī (d. 672 A.H., 1274 C.E.) b. Imām Fakhr al-Dīn, and was brought to Spain by the Arabs, thence a knowledge of its contents was diffused throughout Europe long before the Greek original was discovered. In this work Naṣīr al-Dīn proves most of the propositions, sometimes in two, three, and four ways, wholly different from the demonstrations of the Greek author.