Augustine in His Own Words
(10.14) But since we are investigating the nature of the mind, let us not take into consideration any knowledge that is obtained from the outside, through the senses of the body, but consider more attentively the principle which we have laid down: that every mind knows and is certain concerning itself. For people have doubted whether the powers to live, to remember, to understand, to will, to think, to know, and to judge are due to air or to fire or to the brain or to the blood or to atoms or to a fifth body (I do not know what it is, but it differs from the four customary elements); or whether the combination or the orderly arrangement of the flesh is capable of producing these effects. Some try to maintain this opinion; others, that opinion. On the other hand, who could doubt that one lives and remembers and understands and wills and thinks and judges? For even if one doubts, one lives; if one doubts, one remembers why one doubts, for one wishes to be certain; if one doubts, one thinks; if one doubts, one knows that one does not know; if one doubts, one judges that one ought not to comment rashly. Whoever then doubts about anything else ought never to doubt about all of these; for if they were not, one would be unable to doubt about anything at all.40
Trinitarian Analogy of Memory,
Understanding, and Will
At the end of Book 10, Augustine shifts rather abruptly from his previous triad to a new one: memory (memoria), understanding (intelligentia), and will (voluntas). Here Augustine plays on his experience as an educator. He knows how the young eagerly search for knowledge and delight in discovery. He also notes that education in the best sense involves not only learning new things but also shaping students' morals and character. That seems to Augustine an apt paradigm for believers who, as God's "little ones," search for God. This new analogy is one that he will take up again at the end of On the Trinity. It is also one that medieval thinkers like Bonaventure would appeal to.41 Note that Augustine does not see these three as "faculties" (as some medievals would), but as distinguishable dynamisms within the united mind: that is, the whole mind remembering; the whole mind understanding; the whole mind willing. From On the Trinity, Book 10:
40. Trin. 10.10.14 (CCL 50:327–28); trans. McKenna, FOTC 45:308. Here doubt becomes a proof of existence. Augustine argues in a similar way, "If I am mistaken, I exist" (si fallor, sum) in civ. Dei 11.26 (CCL 48:345–46); see also Trin. 15.12.21. On this, see Rist, Augustine, 63–67; Gareth B. Matthews, Thought's Ego in Augustine and Descartes (Ithaca: Cornell University Press, 1992).
41. For example, Bonaventure, Itinerarium mentis ad Deum 3.5. On this, see William Harmless, "Mystic as Cartographer: Bonaventure," Mystics (New York: Oxford University Press, 2008), 79–105.