The germ of the highest scientific conceptions is often to be found in common reason. Comte delights in giving as an example one of the discoveries which he most admires, Descartes’ invention of analytical Geometry. To determine at every moment the position of a point in space by its distance from fixed axes: is not that what geographers have been doing for so long in order to determine the longitude and latitude of a place upon the terrestrial sphere? And has not this proceeding itself been suggested to the geographer by simple common sense? For he instinctively seeks to mark the inaccessible points which interest him, by means of their distance from given points or lines. From this the idea of the Cartesian co-ordinates only differs by a superior degree of abstraction and of generality. Thus all men must be regarded as collaborating in the discovery of truth as much as in making use of it. Speaking generally, if the great philosophers and scientific men of genius seem to be the intellectual guides of humanity, it is because they are the first to be affected by each mental revolution. They are the first to pass from a traditional to a new attitude and their example is decisive. But, says Comte, “the changes relating to the method of thinking with originality only become manifest when they are almost accomplished.” The great men whose names are justly authors attached to are, however, more the heralds than the of these changes. 2. Science is the work of all: it must therefore be accessible to all. It is a patrimony common to the whole of mankind; and the inheritance must be taken from no one. As a consequence, the State owes scientific instruction to those who are not in a position to procure it for themselves. Not that all men, all the people ought to acquire a deep knowledge of the several fundamental sciences, like those who make it the particular occupation of their lives. The impossibility of such a thing is too evident for several reasons. Neither is it a question of popularising the great scientific theories, for the use of badly prepared minds. Comte condemns severely this way of “simplifying” science. For instance, he will not allow Newton’s laws to be separated from their demonstrations. It will always be the duty of the greater number of men to adopt the majority of scientific truths on the testimony of those who will have discovered, criticised and verified them. But, what it will be the duty of common education to give to every mind, is the habit of conceiving all phenomena, from the most simple to the most complex, as equally governed by invariable laws, and, consequently, of understanding the whole of nature as an order which the positive method alone allows us to discover and to modify. And as this method cannot be studied apart from the sciences in which it is used, it will be necessary for every man to be made acquainted with a summary of each fundamental science, from mathematics to sociology.