In order to validate the classical claim to know autonomous being, the author defends Husserl's methodological principle "Back to things themselves" from empiricist and idealist critics, including the later Husserl, and replies to the arguments of Kant which attempt to discredit the knowability of things in themselves. Originally published in 1982, this book culminates in a phenomenological and critical unfolding of the Augustinian , as giving access to immutable truth about necessary essences and the real existence of personal being.