You will note that by this term 'substance' I understand generally the being endowed with some primitive quality, apart from all special and secondary modifications. If then all the primitive qualities which are known to us can be united in one and the same being, we should only acknowledge one substance; but if there are qualities which are mutually exclusive, there are as many different substances as there are such exclusions. You will think this over; for my own part, whatever Locke may say, it is enough for me to recognise matter as having merely extension and divisibility to convince myself that it cannot think, and if a philosopher tells me that trees feel and rocks think [Footnote: It seems to me that modern philosophy, far from saying that rocks think, has discovered that men do not think. It perceives nothing more in nature than sensitive beings; and the only difference it finds between a man and a stone is that a man is a sensitive being which experiences sensations, and a stone is a sensitive being which does not experience sensations. But if it is true that all matter feels, where shall I find the sensitive unit, the individual ego? Shall it be in each molecule of matter or in bodies as aggregates of molecules? Shall I place this unity in fluids and solids alike, in compounds and in elements? You tell me nature consists of individuals. But what are these individuals? Is that stone an individual or an aggregate of individuals? Is it a single sensitive being, or are there as many beings in it as there are grains of sand? If every elementary atom is a sensitive being, how shall I conceive of that intimate communication by which one feels within the other, so that their two egos are blended in one? Attraction may be a law of nature whose mystery is unknown to us; but at least we conceive that there is nothing in attraction acting in proportion to mass which is contrary to extension and divisibility. Can you conceive of sensation in the same way? The sensitive parts have extension, but the sensitive being is one and indivisible; he cannot be cut in two, he is a whole or he is nothing; therefore the sensitive being is not a material body. I know not how our materialists understand it, but it seems to me that the same difficulties which have led them to reject thought, should have made them also reject feeling; and I see no reason why, when the first step has been taken, they should not take the second too; what more would it cost them? Since they are certain they do not think, why do they dare to affirm that they feel?] in vain will he perplex me with his cunning arguments; I merely regard him as a dishonest sophist, who prefers to say that stones have feeling rather than that men have souls.