Imagination is a sort of faint perception.

A vivid image compels the whole body to follow.

But the whole vital process of the earth takes place so gradually and in periods of time which are so immense compared with the length of our life, that these changes are not observed, and before their course can be recorded from beginning to end whole nations perish and are destroyed.

We can't learn without pain.

It is the active exercise of our faculties in conformity with virtue that causes happiness, and the opposite activities its opposite.

It will contribute towards one's object, who wishes to acquire a facility in the gaining of knowledge, to doubt judiciously.

A friend is another I.