Man believes that he sees clearly, and that he is the measure of all things, while the knowledge that he thinks he has of the world locks him into his complacency: 'If, at midday, we either look down to the ground, or on the surrounding objects which lie open to our view, we think ourselves endowed with a very strong and piercing eyesight', but then if we turn our eyes towards the sun, we are obliged to confess that 'our acuteness in discerning terrestrial objects is mere dimness when applied to the sun'.