All antiquity maintains that our understanding contains nothing which has not been received by our senses. Descartes, on the contrary, asserts in his "Romances," that we have metaphysical ideas before we are acquainted with the nipple of our nurse. A faculty of theology proscribed this dogma, not because it was erroneous, but because it was new. Finally, however, it was adopted, because it had been destroyed by Locke, an English philosopher, and an Englishman must necessarily be in the wrong. In fine, after having so often changed opinion, the ancient opinion which declares that the senses are the inlets to the understanding is finally proscribed. This is acting like deeply indebted governments, who sometimes issue certain notes which are to pass current, and at other times cry them down; but for a long time no one will accept the notes of the said faculty of theology. All the faculties in the world will never prevent a philosopher from perceiving that we commence by sensation, and that our memory is nothing but a continued sensation. A man born without his five senses would be destitute of all idea, supposing it possible for him to live. Metaphysical notions are obtained only through the senses; for how is a circle or a triangle to be measured, if a circle or a triangle has neither been touched nor seen? How form an imperfect notion of infinity, without a notion of limits? And how take away limits, without having either beheld or felt them? Sensation includes all our faculties, says a great philosopher. What ought to be concluded from all this? You who read and think, pray conclude. The Greeks invented the faculty "_Psyche_" for sensation, and the faculty "_Nous_" for mind. We are, unhappily, ignorant of the nature of these two faculties: we possess them, but their origin is no more known to us than to the oyster, the sea-nettle, the polypus, worms, or plants. By some inconceivable mechanism, sensitiveness is diffused throughout my body, and thought in my head alone. If the head be cut off, there will remain a very small chance of its solving a problem in geometry. In the meantime, your pineal gland, your fleshly body, in which abides your soul, exists for a long time without alteration, while your separated head is so full of animal spirits that it frequently exhibits motion after its removal from the trunk. It seems as if at this moment it possessed the most lively ideas, resembling the head of Orpheus, which still uttered melodious song, and chanted Eurydice, when cast into the waters of the Hebrus. If we think no longer, after losing our heads, whence does it happen that the heart beats, and appears to be sensitive after being torn out? We feel, you say, because all our nerves have their origin in the brain; and in the meantime, if you are trepanned, and a portion of your brain be thrown into the fire, you feel nothing the less. Men who can state the reason of all this are very clever. SENTENCES (REMARKABLE).