Aristotle's speech from the Symposium and Descartes' epistemology from his Meditation.

Part I, Question 2: Aristotle distinguishes two kinds of akrasia: impetuosity (propeteia) and weakness (astheneia). The person who is weak goes through a process of reflection and makes a choice; but rather than act in accordance with his reasoned choice, he acts under the influence of a passion. By contrast, the impetuous person does not go through a process of reflection and does not make a reasoned choice; he simply acts under the influence of a …

…he begins by doubting everything, which in my opinion would be the most efficient method of determining what you know vs. what you do not know. By using this process of elimination, you are able to analyze every possible thing and be able to identify truth. In a sense you are questioning the very nature of reality, and by discovering who or what you are as well as the world around you, reality becomes comprehensible.