UNTRUSTWORTHINESS OF THE SENSES

their organs of vision, or is it rigorously true without any mixture of illusion or doubt?”

I then set myself earnestly to examine the notions we derive from the evidence of the senses and from sight in order to see if they could be called into question. The result of a careful examination was that my confidence in them was shaken. Our sight, for instance—perhaps the most practiced of all our senses—observes a shadow, and finding it apparently stationary, pronounces it devoid of movement. Observation and experience, however, show subsequently that a shadow moves; not suddenly, it is true, but gradually and imperceptibly, so that it is never really motionless.

Again, the eye sees a star and believes it to be only as large as a piece of gold The author likely refers to a gold coin, a common medieval trope for visual perspective, but mathematical calculations prove, on the contrary, that it is larger than the earth. These notions, and all others which the senses declare true, are subsequently contradicted and convicted of falsity in an irrefragable meaning: indisputable or impossible to refute manner by the verdict of reason.

Then I reflected within myself: “Since I cannot trust the evidence of my senses, I must rely only on intellectual notions based on fundamental principles, such as the following axioms: self-evident truths that require no proof: ‘Ten is more than three.’ ‘Affirmation and negation cannot coexist together.’ ‘A thing cannot be both created and also existent from eternity, living and annihilated simultaneously, at once necessary...’