Those who, in debate, appeal to their qualifications, argue from memory, not from understanding.

He who does not understand the supreme certainty of mathematics is wallowing in confusion.

There is no object so large but that at a great distance from the eye it does not appear smaller than a smaller object near.

Given the cause nature produces the effect in the briefest manner that it can employ.

Never make heads straight on the shoulders, but turn them aside to the right or to the left, even though they look down, or upward, or straight ahead, because it is necessary for them to look lively and awake and not asleep. And do not depict the front or rear half of the whole person so that too much straightness is displaced, one half above or below the other half; and if you should wish to use stiff figures, do so only in portraying old people.

O Lord, thou givest us everything, at the price of an effort.

Man's external form, marvellously constructed, is not much as compared with the divine soul that dwells inside that structure.