within his reach, and he strives to turn them to the best advantage in administering to the wants and increasing the comforts and convenience of his fellow creatures; but all the labors of the professor of geognosy are directed to discover a secret which appears to be hidden from human ken; a secret, the discovery of which would not, as far as we can judge, add any thing to the sum of human happiness. It excites our astonishment therefore, that so many persons of fine genius and brilliant talents should have wasted so much time in forming what are called theories of the earth, who might have been so much better employed in investigating the secondary causes by which the materials composing the crust of this earth obtained their present forms, and in examining the changes which those materials are daily undergoing. But so it is; the curiosity so natural to our species opens the way--the vanity of being supposed to have penetrated deeper than others into the abstruse mysteries of nature urges them forward--the silly pride of having in their own estimations discovered the hidden ways of Providence quickens their zeal; and, such is the love of the marvellous, that if they exhibit only a tolerable degree of ingenuity, and embellish their performances with a few flowers of rhetoric, they are sure to command more attention and praise from the general mass of readers, than can be extorted by the most laborious examination of nature's works. While Martin Lister was ridiculed by Doctor King for the laudable minuteness with which he described the different natural objects he met with in his journey through France, Mr. Thomas Burnet, for a fanciful theory of the earth, was extravagantly lauded by a writer in the Spectator. Saussure crossed the Alps in fourteen places; Humboldt traversed nearly one half of the habitable globe; Cuvier spent seven years in the study of comparative anatomy, as subservient to the study of fossil remains; and Hauy studied geometry for the sole purpose of obtaining a knowledge of crystalography; but neither of these distinguished philosophers have been able to win the laurels that have been heaped upon the brow of Count Buffon for a visionary hypothesis which he calls a theory of the earth. The substitution of these hypotheses for knowledge, unfortunately, has not been confined to the early and dark ages of geology. One entirely new theory of the earth was published as lately as the year 1825--another in 1827--and a third in 1829. It is proper therefore that the student should be warned against their fascinating and baneful influence. For the Southern Literary Messenger. ESSAY ON LUXURY.