For the elements have the property of moving back to their place in a straight line, but they have no properties which would cause them to remain where they are, or to move otherwise than in a straight line. The rectilinear motions of these four elements when returning to their original place are of two kinds, either centrifugal, viz., the motion of the air and the fire; or centripedal, viz., the motion of the earth, and the water; and when the elements have reached their original place, they remain at rest.

The physician should not treat the disease but the patient who is suffering from it

If a person studies too much and exhausts his reflective powers, he will be confused, and will not be able to apprehend even that which had been within the power of his apprehension. For the powers of the body are all alike in this respect.

He, however, who begins with Metaphysics, will not only become confused in matters of religion, but will fall into complete infidelity.

When I have a difficult subject before me - when I find the road narrow, and can see no other way of teaching a well established truth except by pleasing one intelligent man and displeasing ten thousand fools - I prefer to address myself to the one man, and to take no notice whatever of the condemnation of the multitude; I prefer to extricate that intelligent man from his embarrassment and show him the cause of his perplexity, so that he may attain perfection and be at peace.

How individuals of the same species surpass each other in these sensations and in other bodily faculties is universally known, but there is a limit to them, and their power cannot extend to every distance or to every degree.

It is thus necessary to examine all things according to their essence, to infer from every species such true and well established propositions as may assist us in the solution of metaphysical problems.