On First Philosophy

A short metaphysical treatise dedicated to the Abbasid caliph al-Muʿtaṣim, and one of the first works of philosophy written in Arabic. Only its first part survives. Al-Kindī opens by defining philosophy as knowledge of things as they truly are, and first philosophy as knowledge of the First Truth, the cause of every truth. He then defends learning from the Greeks: truth should be welcomed whatever its source, and those who attack philosophy must use reasoning to do so. The second section argues that no actually infinite body, magnitude or time can exist, so the world must have had a beginning in time. The later sections analyse the many senses in which things are called 'one', show that the unity of created things is borrowed from elsewhere, and conclude that there must be a True One, the cause of all unity, which can be described only by saying what it is not.

It is the founding text of philosophy in Arabic, and its argument that the world cannot be infinitely old still lies behind the kalām cosmological argument debated today.