=139. Other duties in regard to the body.--Temperance.=--We have just seen that man has no right to destroy his body, or mutilate it, or, in short, uselessly to reduce or enfeeble its power; in a word, he must not voluntarily injure his physical functions: for, in impairing himself as a physical being, he thereby injures his personality, which is the principle of all morality. But there are two things to be distinguished in the functions of the human body: on one side, their utility, and on the other, the pleasure which attends their healthful exercise. The same function may be exercised with more or less pleasure on the side of the senses. Hence a moral problem: What is to be granted to the pleasures of the senses?--Certainly for the proper exercise of their functions a certain sensuous agreeableness is necessary; a good appetite, for instance, is a pleasant seasoning which excites and facilitates digestion. Nevertheless, we all know that there is not an exact and continued proportion between the pleasure of the senses and physiological necessity; we know that enjoyment may by far exceed necessity, and that health even often requires a certain limitation in enjoyment. We know, for example, that the pleasures of the palate may be far more sought after and prolonged than is necessary for the gratification of the appetite. Man needs very little to live on; but he can continue to tickle his palate long after his hunger is satisfied. Thirst, in particular, has given rise to a multitude of refinements invented by human industry, and which are but very distantly related to the principle which has given them birth. Wine and alcoholic drinks, which, used in moderation, may be useful tonics, are stimulants demanding a constant renewal: the more they are indulged in, the more they provoke and captivate the imagination. From this disproportion and incongruity which exist between the pleasures of the senses and the real wants of the body, arise vices, certain habits, namely, which sacrifice want to pleasure, and the consequence of which is the depravation and ruin of the natural functions. Pleasure, in fact, is, in a certain measure, the auxiliary, and in some sort, the interpreter of nature; but beyond a certain limit, it can only satiate itself at the expense of the legitimate function, and by solidarity, at the expense of all the others. Thus too much eating destroys the digestive functions; stimulating drinks burn the stomach and seriously injure the nervous system. The same, and with still graver consequences, attends upon the pleasures attached to the function of reproduction.