Aristotle

Education is the best provision for old age.

The roots of education are bitter, but the fruit is sweet.

Every science and every inquiry, and similarly every activity and pursuit, is thought to aim at some good.

We are what we repeatedly do. Excellence then, is not an act, but a habit.

Friendship is a single soul dwelling in two bodies.

Aristotle suggests that the rotating Earth was a generally accepted tenet of Pythagorism: "While most of those who hold that the whole heaven is finite say that the earth lies at the center, the philosophers of Italy, the so-called Pythagoreans, assert the contrary. They say that in the middle there is fire, and that the earth is one of the stars, and by its circular motion round the center produces night and day."

It is the mark of an educated mind to rest satisfied with the degree of precision which the nature of the subject admits and not to seek exactness where only an approximation is possible.

Character is that which reveals moral purpose, exposing the class of things a man chooses or avoids

Aristotle's geographical speculations anticipated by almost two thousand years the rationale behind Columbus' voyage. Ferdinand Columbus suggested that his father was familiar with the following passage: "Again, our observations of the stars make it evident, not only that the earth is circular, but also that it is a circle of no great size. For quite a small change of position to south or north causes a manifest alteration of the horizon. There is much change, I mean, in the stars which are overhead, and the stars seen are different, as one moves northward or southward. . . . All of which goes to show not only that the earth is circular in shape, but that it is a sphere of no great size: for otherwise the effect of so slight a change of place would not be so quickly apparent. Hence, one should not be too sure of the incredibility of the view of those who conceive that there is a continuity between the parts about the pillars of Hercules [the strait of Gibraltar] and the parts about India, and that in this way the ocean is one."

To be conscious that we are perceiving or thinking is to be conscious of our own existence.