Philosophy begins where science ends. Philosophy has ceased to be a science. It is a source of its own. The limits of science make obvious that faith belongs to being human. Faith is either religious or philosophical. Faith is a main phenomenon of being human. It consists in the simple fact that persons have ultimate convictions. Philosophical faith is existential faith. Its certainty is tied to the individual. Philosophical faith cannot be achieved without personal effort, without acts of actual freedom, and without realizations of Existenz. Jaspers' concept of philosophical faith turns out to be a new synthesis of historical conditions and philosophical requirements.