The Virtuous City (Principles of the Opinions of the People of the Virtuous City)

A systematic treatise that moves from God to the ideal society, written in Baghdad and finished in Damascus late in al-Fārābī's life. It begins with the First Being, perfect, one and without cause, from which proceed a series of intellects and the heavenly spheres, ending with the Active Intellect that governs the world below the moon. It then describes matter and form, the elements, and the faculties of the human soul, rising to the intellect. Prophecy is explained as the Active Intellect acting on an exceptionally strong imagination, so that the prophet receives in images what the philosopher grasps in concepts. The book then compares the virtuous city to a healthy body ruled by its heart: its first ruler unites philosophy and prophecy, and its people cooperate toward true happiness. Against it stand the ignorant, the immoral, the changed and the errant cities, each built on a false idea of happiness, and al-Fārābī describes the fate of each kind of soul after death.

It is the classic statement of the falsafa picture of cosmos and city, showing how a medieval philosopher joined Plato's Republic to Neoplatonic metaphysics and an Islamic account of prophecy.