XLV. With all the principles and causes hitherto pointed out, of error in history, co-operates that of little reading. He who reads little, frequently mistakes the doubtful for the certain, and sometimes the false also. Generally speaking, in all the human theoretic faculties, much study produces an effect different from that produced by mathematical study. In this last science, the more a man studies, the more he knows; in the others, the more he reads, the more he doubts. In the mathematics, the study proceeds to remove doubts; in the others, it goes on to increase them. For instance, he who studies philosophy only under one master, all that master says, provided he is one of those who speak positively and decidedly, he takes for granted. If he afterwards extends his inquiries, and has recourse to others, although they should be of the same school, the Aristotelic for example, he will begin to entertain doubts, which will be occasioned by the nature of their disputes among themselves; but he will still retain a firm assent to the principles in which they are all agreed. If he afterwards reads with reflexion, and free from all prejudice or pre-occupation, the works of authors of other sects, he will begin to entertain doubts of even the principles themselves. XLVI. The same thing happens with respect to history. He who reads a general history of the world, a kingdom, or a century, in one author only, takes for granted all that is advanced by that author; and when, in any future time, it occurs to him to speak or to write on the subject, he asserts with confidence all he has read in that author. If, afterwards, he applies himself to read books written by other authors on the same subject, he will begin to entertain doubts of what he read in the first, and the further he extends his reading, the more he will increase his doubts; it being infallible, that the new contradictions which he will ever find in authors, must beget in his mind a succession of fresh doubts, till at last he will perceive many relations to be either false or doubtful, which, in the beginning, he looked upon as absolutely certain. XLVII. In order to give a palpable demonstration of this truth, and to point out some of the common errors of history, which is the principal object I always have in view; I will introduce in this place, a catalogue of many and various events of different ages; which already in the general run of books, and the opinion of the vulgar, pass for indisputable, and will, at the same time, state together with them, the reasons for placing them in a doubtful point of view, or the evidence which convicts them of falsehood. SECT. XVI. _The beautiful Helen._