In a single principle, opening as it were on a sudden to genius, a great and new system of things is discovered.

It has happened, sometimes, that this single conception, rushing over the whole concentrated spirit, has agitated the frame convulsively.

It comes like a whispered secret from Nature.

When MALEBRANCHE first took up Descartes's Treatise on Man, the germ of his own subsequent philosophic system, such was his intense feeling, that a violent palpitation of the heart, more than once, obliged him to lay down the volume.

When the first idea of the "Essay on the Arts and Sciences" rushed on the mind of ROUSSEAU, a feverish symptom in his nervous system approached to a slight delirium.