Those who wish to study Nature, must take experience for their guide; this, and this only, can enable them to dive into her secrets, to unravel by degrees, the frequently imperceptible woof of those slender causes, of which she avails herself to operate the greatest phenomena: by the aid of experience, man often discovers in her properties, perceives modes of action entirely unknown to the ages which have preceded him; those effects which his grandfathers contemplated as marvellous, which they regarded as supernatural efforts, looked upon as miracles, have become familiar to him in the present day, and are at this moment contemplated as simple and natural consequences, of which he comprehends the mechanism--of which he understands the cause--of which he can unfold the manner of action. Man, in fathoming Nature, has arrived at discovering the true causes of earthquakes; of the periodical motion of the sea; of subterraneous conflagrations; of meteors; of the electrical fluid, the whole of which were considered by his ancestors, and are still so by the ignorant, by the uninformed, as indubitable signs of heaven's wrath. His posterity, in following up, in rectifying the experience already made, will perhaps go further, and discover those causes which are totally veiled from present eyes. The united efforts of the human species will one day perhaps penetrate even into the sanctuary of Nature, and throw into light many of those mysteries which up to the present time she seems to have refused to all his researches.