It was Gassendi's opinion, as may be seen in his objections to Descartes. "It is true," says Gassendi, "that you know what you think; but you are ignorant of what species of substance you are, you who think. Thus although the operation of thought is known to you, the principle of your essence is hidden from you; and you do not know what is the nature of this substance, one of the operations of which is to think. You are like a blind man who, feeling the heat of the sun and being informed that it is caused by the heat of the sun, thinks he has a clear and distinct idea of this luminary; because if he were asked what the sun was, he could reply that it is a thing which heats, etc."
The same Gassendi, in his "Epicurean Philosophy," repeats several times that there is no mathematical evidence of the pure spirituality of the soul.
Descartes, in one of his letters to the Palatine Princess Elisabeth, says to her—"I confess that by the natural reason alone we can make many conjectures on the soul, and have gratifying hopes, but no certainty." And in that sentence Descartes combats in his letters what he puts forward in his works; a too ordinary contradiction.
In fine we have seen that all the Fathers of the first centuries of the Church, while believing the soul immortal, believed it at the same time material; they thought that it is as easy for God to conserve as to create. They said—"God made the soul thinking, He will preserve it thinking."
Malebranche has proved very well that we have no idea by ourselves, and that objects are incapable of giving us ideas: from that he concludes that we see everything in God. That is at the bottom the same thing as making God the author of all our ideas; for with what should we see in Him, if we had not instruments for seeing? and these instruments, it is He alone who holds them and guides them. This system is a labyrinth, one lane of which would lead you to Spinozism, another to Stoicism, another to chaos.
When one has had a good argument about spirit and matter, one always finishes by not understanding each other. No philosopher has been able with his own strength to lift this veil stretched by nature over all the first principles of things. Men argue, nature acts.
SECTION III
Of the Soul of Animals, and of some Empty Ideas
Before the strange system which supposes animals to be pure machines without any sensation, men had never thought that the beasts possessed an immaterial soul; and nobody had pushed recklessness to the point of saying that an oyster has a spiritual soul. Everyone concurred peaceably in agreeing that the beasts had received from God feeling, memory, ideas, and no pure spirit. Nobody had abused the gift of reason to the point of saying that nature had given the beasts all the organs of feeling so that they might not feel anything. Nobody had said that they cry when they are wounded, and that they fly when pursued, without experiencing pain or fear.
At that time people did not deny the omnipotence of God; He had been able to communicate to the organized matter of animals pleasure, pain, remembrance, the combination of a few ideas; He had been able to give to several of them, such as the monkey, the elephant, the hunting-dog, the talent of perfecting themselves in the arts which were taught to them; not only had He been able to endow nearly all carnivorous animals with the talent of warring better in their experienced old age than in their too trustful youth; not only, I say, had He been able to do these things, but He had done them: the universe bore witness thereto.