This art, which I call the art of persuading, and which, properly speaking, is simply the process of perfect methodical proofs, consists of three essential parts: of defining the terms of which we should avail ourselves by clear definitions, of proposing principles of evident axioms to prove the thing in question; and of always mentally substituting in the demonstrations the definition in the place of the thing defined.

There are hardly any truths upon which we always remain agreed, and still fewer objects of pleasure which we do not change every hour, I do not know whether there is a means of giving fixed rules for adapting discourse to the inconstancy of our caprices.

The principles of pleasure are not firm and stable. They are different in all mankind, and variable in every particular with such a diversity that there is no man more different from another than from himself at different times.

The art of persuasion consists as much in that of pleasing as in that of convincing, so much more are men governed by caprice than by reason!

It is necessary to have regard to the person whom we wish to persuade, of whom we must know the mind and the heart, what principles he acknowledges, what things he loves; and then observe in the thing in question what affinity it has with the acknowledged principles, or with the objects so delightful by the pleasure which they give him.

A doubtful balance is made between truth and pleasure, and... the knowledge of one and the feeling of the other stir up a combat the success of which is very uncertain, since, in order to judge of it, it would be necessary to know all that passes in the innermost spirit of the man, of which man himself is scarcely ever conscious.

As soon as the soul has been made to perceive that a thing can conduct it to that which it loves supremely, it must inevitably embrace it with joy.

Several particular maxims... are as powerful, although false, in carrying away belief, as those the most true.

Of the truths within our reach... the mind and the heart are as doors by which they are received into the soul, but... few enter by the mind, whilst they are brought in crowds by the rash caprices of the will, without the council of reason.

God only pours out his light into the mind after having subdued the rebellion of the will by an altogether heavenly gentleness which charms and wins it.