St Augustine who during his formation in philosophy had made contact with the Scepticism of the academicians, knew that the problem of knowledge involved two difficulties one regarding the existence of the knowing subject which fact was denied by the academicians and the other regarding the origin of knowledge itself. As for the first question St Augustine overcame Scepticism of the Academy and arrived at the affirmation of the existence of the knowing subject with the famous argument: “if I doubt, I exist
Regarding the second question the origin of knowledge St. Augustine as a Platonist underrates sensitive understanding, which he does not make the foundation of intellective knowledge. Thus he differs radically from Aristotle and Thomism inn this important question whence, then does intellective cognition draw its origin? From illumination. As the eyes have need of the light of the sun in order to see sensible objects,, so the intellect needs the light of in order to see sensible objects, so the intellect needs the light of God to know the world of intangible beings. Eternal truths, ideas species, formal principles are imparted to our intelligence by wisdom the word of God. Intellectual knowledge is not result of the acquisitive operation of the intellect but a participation or grant of God. It is in this participation that Augustines innitism with regard to ideas consists. It follows from this that the intellect, considered in itself is in capable of such knowledge through illumination. The Mystic schools of the middle ages were to appeal to this natural inability of the intellect in order to affirm that humility and prayer are the best means to acquiring wisdom.