All the pieces of the machine of this world seem, however, made for each other. A few philosophers affect to mock at the final causes rejected by Epicurus and Lucretius. It is, it seems to me, at Epicurus and Lucretius rather that they should mock. They tell you that the eye is not made for seeing, but that man has availed himself of it for this purpose when he perceived that eyes could be so used. According to them, the mouth is not made for speaking, for eating, the stomach for digesting, the heart for receiving the blood from the veins and for dispatching it through the arteries, the feet for walking, the ears for hearing. These persons avow nevertheless that tailors make them coats to clothe them, and masons houses to lodge them, and they dare deny to nature, to the great Being, to the universal Intelligence, what they accord to the least of their workmen. Of course one must not make an abuse of final causes; we have remarked that in vain Mr. Prieur, in "The Spectacle of Nature," maintains that the tides are given to the ocean so that vessels may enter port more easily, and to stop the water of the sea from putrefying. In vain would he say that legs are made to be booted, and the nose to wear spectacles. In order that one may be certain of the true end for which a cause functions, it is essential that that effect shall exist at all times and in all places. There were not ships at all times and on all the seas; hence one cannot say that the ocean was made for the ships. One feels how ridiculous it would be to maintain that nature had worked from all time in order to adjust herself to the inventions of our arbitrary arts, which appeared so late; but it is quite evident that if noses were not made for spectacles, they were for smelling, and that there have been noses ever since there have been men. Similarly, hands not having been given on behalf of glove-makers, they are visibly destined for all the purposes which the metacarpal bones and the phalanges and the circular muscle of the wrist may procure for us. Cicero, who doubted everything, did not, however, doubt final causes. It seems especially difficult for the organs of generation not to be destined to perpetuate the species. This mechanism is very admirable, but the sensation which nature has joined to this mechanism is still more admirable. Epicurus had to avow that pleasure is divine; and that this pleasure is a final cause, by which are ceaselessly produced sentient beings who have not been able to give themselves sensation.