=106. IV. Science--Teaching--Medicine--The letters and arts.=--Beside the _social powers_ which _make_, _execute_ and _apply_ the laws, there is _science_, which instructs men, enlightens them, directs their work, and which even, setting utility aside, is yet in itself an object of disinterested research. Side by side with the sciences are the letters and arts, which pursue and express the _beautiful_, as science pursues the _true_. Finally, to science and art are added _morality_ and _religion_, whose object is the _good_. The moralists, it is true, do not constitute a particular profession in society, or at least their part is blended with teaching in general; religion has its interpreters, who find in their dogmas and traditions the rules of their duties. It is not the business of lay morality to teach these. Let us, therefore, content ourselves with a few principles concerning the sciences and letters. =107. Science--Duties of Scientists.=--Science may be cultivated in two different ways and from two different standpoints: 1, for itself; 2, for its social advantages--for the services it renders to men. There is but a small number of men who have a natural taste for pure science, and the leisure to give themselves up to the love of it; but those who choose such a life contract thereby certain duties. The first of all is the _love of truth_. The only object for the scientist to pursue is truth. He must, therefore, lay aside all interests and passions antagonistic to truth; and, above all, personal interest which inclines one to prefer one theme to another, because of the advantages it may bring; this is, however, so gross a motive, that it would not be supposed to exist with a true scholar; yet are there other causes of error no less dangerous--for example, the interest of a cause--of a conviction which is dear to us; the interest of our self-love, which makes us persist in error known to be such; the spirit of system, by which one shows his peculiar forte, etc. All these passions should give way before the pure love of truth. =108. The communication of science--Teaching.=--The principal duty of those who are possessed of science is to communicate it to other men. Certainly, all men are not called to be scholars; but all should in some degree have their intelligence cultivated by _instruction_. Hence the duty of teaching imposed upon scholars; but this duty brings with it many others. 1. The masters who teach others should themselves first be educated. Hence the duty of intellectual work, not merely to acquire knowledge, without which one cannot be a teacher, but to preserve and increase it. The teacher should, therefore, set an example to his pupil of assiduous and continuous intellectual work.