When the historians of the Conquest wrote their marvelous narratives of alleged adventures and of the new empire, it was a question for the Emperor and the Inquisition solely, whether their writings should pass for history or be condemned as fabulous. With this question the people had nothing to do but to believe as it suited those in authority. The question being settled that the publication of the letters of Cortez as a verity would redound to the glory of the Church and the king, then it was also settled that there should be no contradiction published; and as these marvelous tales were spread abroad throughout Europe, with the masses of silver from the newly-discovered mines, men were prepared to believe almost any thing--even that rich vegetable mould, when saturated with water, could float. It not being lawful to promulgate the facts of the Conquest, the memory of events that really transpired ultimately passed from the recollections of men, so that the letters of Cortez were taken for truth, even in their most minute details; so that, in a subsequent century, we find a vice-king employing an engineer to search for and clean out the hole in the bottom of the Tezcuco! for, from the vice-king down to the most insignificant official, all assumed that the letters of Cortez gave a correct picture of affairs at that time; and all showed the greatest embarrassment in accounting for the magnitude of the changes that are supposed to have occurred without a sufficiently adequate cause. It is a common difficulty in all purely Catholic countries, for there the rule of evidence is an unnatural one. The people have been taught to believe from their infancy that the laws of nature can be set aside upon every trifling occasion, at the momentary caprice of any one of the multitude of saints "who are to govern the world;" and on proof that any mortal has set aside the laws of nature or wrought a miracle, he at once becomes a saint. With these "dutiful children of the Church" there can be no fixed laws of evidence; the only ground of belief is, and ever must be, Has the statement been sanctioned by the highest authority? If so, it is true; if not, it is to be doubted, however positive the proofs may be. A difficulty that the traveler every where encounters is that he can believe nothing that he hears, even on the most trifling subject, without careful examination and weighing of testimony. As he can not examine every thing himself, he is constantly liable to be imposed upon by taking for granted that which is every where affirmed. Humboldt for once, with all his caution, seems to have fallen into the common trap, and credited, without examination, the story of the floating gardens. THE CHINAMPAS.