 Later, Augustine will draw on his theory of illumination to provide the grounds for certainty. According to this theory, God’s Divine Ideas serve as the guarantors of certainty, and they function in much the way that Plato’s Forms do. Augustine first presents this view in De Magistro (On the Teacher), and he makes other references to it in later works. Augustinian Illumination has been widely discussed in the secondary literature, and Nash (1969) still remains one of the best introductions to the position.