We have spoken of two essential attributes of matter, upon which depend the greater number of its properties, namely extension and moving force. We have now but to prove a third attribute: I mean the faculty of feeling which the philosophers of all centuries have found in this same substance. I say all philosophers, although I am not ignorant of all the efforts which the Cartesians have made, in vain, to rob matter of this faculty. But in order to avoid insurmountable difficulties, they have flung themselves into a labyrinth from which they have thought to escape by this absurd system "that animals are pure machines."{89} An opinion so absurd has never gained admittance among philosophers, except as the play of wit or as a philosophical pastime. For this reason we shall not stop to refute it. Experience gives us no less proof of the faculty of feeling in animals than of feeling in men.... There comes up another difficulty which more nearly concerns our vanity: namely, the impossibility of our conceiving this property as a dependence or attribute of matter. Let it not be forgotten that this substance reveals to us only ineffable characters. Do we understand better how extension is derived from its essence, how it can be moved by a primitive force whose action is exerted without contact, and a thousand other miracles so hidden from the gaze of the most penetrating eyes, that (to paraphrase the idea of an illustrious modern writer) they reveal only the curtain which conceals them? But might not one suppose as some have supposed, that the feeling which is observed in animated bodies, might belong to a being distinct from the matter of these bodies, to a substance of a different nature united to them? Does the light of reason allow us in good faith to admit such conjectures? We know in bodies only matter, and we observe the faculty of feeling only in bodies: on what foundation then can we erect an ideal being, disowned by all our knowledge? However, we must admit, with the same frankness, that we are ignorant whether matter has in itself the faculty of feeling, or only the power of acquiring it by those modifications or forms to which matter is susceptible; for it is true that this faculty of feeling appears only in organic bodies. This is then another new faculty which might exist only potentially in matter, like all the others which have been mentioned; and this was the hypothesis of the ancients, whose philosophy, full of insight and penetration, deserves to be raised above the ruins of the philosophy of the moderns. It is in vain that the latter disdain the sources too remote from them. Ancient philosophy will always hold its own among those who are worthy to judge it, because it forms (at least in relation to the subject of which I am treating) a system that is solid and well articulated like the body, whereas all these scattered members of modern philosophy form no system. APPENDIX.