Carefully composed over twenty years, Newman’s Essay in Aid of a Grammar of Assent is an acknowledged masterpiece both for its apologetic response to atheistic naturalism and its positive contribution to the Catholic theology of faith. Newman confronts the dilemma of modern skepticism through a sustained investigation of what it means for the mind to give assent. He shows how the believer, who encounters the light of Christ, can give a certain assent to the propositions of the faith even in the absence of demonstrative proof.