THÉOTIME. It is necessary, Theodore, that I tell you about an experiment I did [une expérience que j'ai faite]. One day in summer I took a large piece of meat that I enclosed in a bottle and covered it with a bit of gauze. I noticed that various flies came to lay their eggs or larvae on this gauze and that, when they hatched, they ate the gauze and fell onto the meat, which they devoured in a short time. But as that smelled too bad, I threw it all out.
THÉODORE. That is how flies 'come from' putrefaction. They put their larvae on the meat and hurriedly fly away. These larvae eat and the flesh putrefies. After those larvae have eaten well, they enclose themselves in their cocoons and leave them as flies; and because of this common men believe insects come from putrefaction.
THÉOTIME. What you say is certain. For many times I have enclosed flesh in a hermetically sealed bottle where no flies have been, and I have never found larvae there.
ARISTE. But how then can it be that one finds very large ones in all sorts of fruits?
THÉODORE. One finds them large, but they entered the fruits small. Search well, you will discover on the skin either a small hole or its scar. But let us not dwell, I beg you, on the proofs that people give that there are animals that come from putrefaction. For these are proofs so weak that they do not merit any reply. 'One finds mice in a newly constructed vessel, or in a place where there were none. Therefore, it must be that this animal has been engendered from some putrefaction.' As if these animals were prevented from seeking out their needs at night, from moving on planks and and on the ropes onto small boats and from there onto the large ships, or as if one could construct vessels elsewhere than on the shore! I cannot comprehend how so many people of good sense have been able to enter into such a blatant and palpable error for reasons like this. For what is there that is more incomprehensible than an animal being formed naturally out of a little putrified meat? It is infinitely easier to conceive of a bit of rusty iron being changed into a perfectly good watch; for there are infinitely more parts of greater delicacy in a mouse than in the most complex clock.
Nicolas Malebranche, Dialogues on Metaphysics and on Religion (1688), XI.viii.
I posted this passage, with some slight differences in translation and a brief note relating it to Redi and Pasteur, previously. Another interesting thing about this passage is Malebranche's infinite machine theory of animal life -- when Théodore says there are infinitely more parts of greater delicacy in a mouse than in the most complex clock, he means it literally. On a Cartesian view, of course, all animals are merely complex machines -- elaborate systems of moving parts. What, then, is there to distinguish manmade machines from animals? As far as I recall, Descartes doesn't give us any such distinguishing feature, being more interested in distinguishing humans (who are animal machines with the Cartesian soul) from mere animals. It's possible that he didn't think there was any essential difference. Malebranche, however, does give a clear distinguishing feature: artificial machines are finite machines; natural machines, like animals, are infinite machines. Keep in mind that Malebranche, as a Cartesian, believes that matter is infinitely divisible; so there isn't any theoretical problem with animals having an infinity of parts. And Malebranche held that heredity provided a good reason to believe that animals were actually divided into infinite parts -- Malebranche was (to an extent) a preformationist, so he thought the reason why all bees resemble the first bee is that all bees that have been generated from other bees were originally preserved in very minute germinal form in their predecessors. So baby bee was originally just a tiny part of its mother, who was originally just a tiny part of its mother, who was originally just a tiny part of its mother, on until we reach the very first bee. It's a beautiful picture, actually, and he is right that it would have accounted for all the facts in a simple and elegant way: all heredity and generation would be merely the unfolding (according to simple natural laws) of a complexity implicit in the original creation. (In a previous post I briefly summarized some aspects of Malebranche's view of heredity, which focuses more on the ways in which Malebranche has adjusted his preformationist view to take account of facts that seem to favor epigenesis.) In a sense, it's too bad that animals aren't infinite machines and that heredity isn't an unfolding of complexity. The great Cartesian cosmos-machine unfolding, budding, flowering into new animals, would be quite impressive.
Notice, by the way, the metaphor of the clock. In The Search after Truth Malebranche constructs a design argument that uses the metaphor of the watch. Like most design arguments up to that point, however, it is not an argument for God's existence but for divine providence. In particular, it is an attack on the Epicurean view that the universe came to be entirely due to the random motions of atoms in a void:
But if one examines the reasons and purpose of all these things, one will find so much order and wisdom that a little serious thought will convince even the most devoted disciples of Epicurus and Lucretius that there is a providence which rules the world. When I see a watch, I have a reason to conclude that there is an intelligence, because it is impossible that chance could produce and arrange all its wheels. How then would it be possible for chance, and the encounter of atoms, to be capable of arranging in all men and in all the animals so many different forces, with the precision and proportion that I have just explained? And how, by chance, could it happen that men and animals procreate other beings that exactly resemble them? Thus it is simply ridiculous to think or to say with Lucretius that chance formed all the parts that make up a man, that eyes were not made in order to see, but rather that one thinks of seeing because one has eyes, and similarly with the other parts of the body. (Lennon-Olscamp translation, p. 98)
Malebranche connects this design aspect of the infinite machine hypothesis to a number of theses: only God can make animals (because only God could make a machine of infinite parts); animals do not need souls to do what they do (because an infinite machine is able to do anything that can be done with infinite parts working together in a systematic way); we are not true causes of anything that happens in our body (because to do so we would have to operate the infinite parts of our own infinite machine); indeed, nothing except God is a true cause at all when it comes to matters of life (because only He has the infinite knowledge and foreknowledge that would be required to handle infinite machines).
While Malebranche seems to have been the originator of the hypothesis, the most famous proponent of it is Leibniz. As he says in the Monadology:
Thus the organic body of each living being is a kind of divine machine or natural automaton, which infinitely surpasses all artificial automata. For a machine made by the skill of man is not a machine in each of its parts. For instance, the tooth of a brass wheel has parts or fragments which for us are not artificial products, and which do not have the special characteristics of the machine, for they give no indication of the use for which the wheel was intended. But the machines of nature, namely, living bodies, are still machines in their smallest parts ad infinitum. It is this that constitutes the difference between nature and art, that is to say, between the divine art and ours. (#64; Montgomery translation)