Giving souls strong individuality is one of Plato's most influential but also most controversial innovations. This book addresses such souls' agency, which is a prerequisite of their many functions not only in human life but in the universe at large. Its conclusion is that the agency proper to the soul stands apart from other Platonic causes as the only full-blooded agent whose actions and passions organize our short moral and civic life, all the while participating, thanks to the soul's immortal existence and repeated incarnation, in the maintenance of the cosmos as a home to innumerable living species. Together with treating this multitude of the soul's tasks, the book pays attention to the unavoidable personification of the soul and to the carefully constructed images that impress on the reader its complexity.