No one is wise at all times.

The ancients had little doubt about the true shape of the earth: "It's [the world's] shape has the rounded appearance of a perfect sphere. This is shown first of all by the name of 'orb' which is bestowed upon it by the general consent of mankind. ...Our eyesight also confirms this belief, because the firmament presents the aspect of a concave hemisphere equidistant in every direction, which would be impossible in the case of any other figure."

When a building is about to fall down, all the mice desert it.

The largest land animal is the elephant, and it is the nearest to man in intelligence: it understands the language of its country and obeys orders, remembers duties that it has been taught, is pleased by affection and by marks of honour, nay more it possesses virtues rare even in man, honesty, wisdom, justice, also respect for the stars and reverence for the sun and moon.

The most valuable discoveries have found their origin in the most trivial accidents.

Man is the only one that knows nothing, that can learn nothing without being taught. He can neither speak nor walk nor eat, and in short he can do nothing at the prompting of nature only, but weep.

In these matters the only certainty is that nothing is certain.