The essay is preceded by a preface in which the origin, purpose and method of the anthology is explained. The two ends of instruction, we are told,[4] are learning and character, and of these the latter is the more important. But there are many books, and especially books of epigrams, that are quite filthy and obscene. Young people are led by curiosity to read these, and losing all chastity of mind enter upon a progressive corruption of life. It would be best if they could be kept wholly from such books; but there is a good deal in them of genuine profit and literary merit, which makes it difficult to keep them wholly out of the hands of youth. Therefore the editor undertook to expurgate the epigrammatists, especially Catullus and Martial. He was horrified when he read over their works, but he found some good among the bad, as in vipers not everything is poisonous but some things even useful to health. His primary purpose, then, was to protect the good young man from being harmed and to leave him no excuse for wishing to have or peruse such books since the good in them had already been extracted for him. The difficulty then arose of making the selection serve the purposes both of morality and of judgement. The editor could either gather together all the epigrams that were not obscene, or he could choose only the best. He took in fact both ways: he preserved everything of Catullus and Martial except the cheapest odds and ends and filthiest obscenities, and he applied strict standards of judgement to the rest so that, unless an epigram had literary merit or contained something worth knowing, he felt there was no reason to burden the book with it. Nevertheless, some middling epigrams found entrance into the anthology--he confesses the fact so the reader will not look for excellence without flaw. The reasons were, first, that the complete perfection he was looking for is seldom or never attained. Hence, if he had admitted only those epigrams in which there was nothing to censure, the task would not have been one of selecting some but rather of rejecting almost all. Again, in epigrams dealing with memorable events or in praise of famous men, sometimes he looked to the profit of the work rather than to its polish, as in Ausonius' quatrains on the Caesars. Finally, he will not deny that chance has played its part against his will. As a judge after a series of severe sentences will give a lighter one to a man no less guilty than the others, so after rejecting a great number of epigrams by some writer a sense of pity arose and a distaste with severity of judgement; then if anything that seemed pointed turned up, though no better than what was rejected, he could not bear to see it discarded. This has occasionally happened, but hardly ever without a warning note to the reader.