Abstract: This chapter begins with a brief introduction to the life of Karl Rahner and then deals with his theological and philosophical method, asserting the priority of the former over the latter. The influence of Transcendental Thomism is dealt with by examining how the thought of Thomas Aquinas and Immanuel Kant affected Rahner's analysis of human knowledge, the ‘Vorgriff’ (preapprehension), and transcendental experience.Rahner believed that transcendental experience showed human nature to be personal, free, and responsible, and consisting of a unity of matter and spirit. The chapter concludes by showing how this analysis of human experience fits with Rahner's key theological idea of God as both mystery and revelation. He sought to explain that God's self-communication to humanity is both due to grace and intrinsic to human nature (the ‘supernatural existential’) and that it is the perfection of this that constitutes salvation.

Keywords: Aquinas, grace, human nature, Kant, life, mystery, philosophy, revelation, supernatural existential, Transcendental Thomism,