It was this ethical and civilizing function of poetry which was first in the minds of the humanists. Action being the test of all studies,[20] poetry must stand or fall in proportion as it conduces to righteous action. Thus, Lionardo Bruni[21] speaks of poetry as "so valuable an aid to knowledge, and so ennobling a source of pleasure"; and AEneas Sylvius Piccolomini, in his treatise _De Liberorum Educatione_ (1450), declares that the crucial question is not, Is poetry to be contemned? but, How are the poets to be used? and he solves his own question by asserting that we are to welcome all that poets can render in praise of integrity and in condemnation of vice, and that all else is to be left unheeded.[22] Beyond this, the humanists urged in favor of poetry the fact of its antiquity and divine origin, and the further fact that it had been praised by great men of all professions, and its creators patronized by kings and emperors from time immemorial. There were then at the end of the Middle Ages, and the beginning of the Renaissance, two opposing tendencies in regard to the poetic art, one representing the humanistic reverence for ancient culture, and for poetry as one of the phases of that culture, and the other representing not only the mediaeval tradition, but a purism allied to that of early Christianity, and akin to the ascetic conceptions of life found in almost every period. These two tendencies are expressed specifically in their noblest forms by the great humanist Poliziano, and the great moral reformer Savonarola. In the _Sylvae_, written toward the close of the fifteenth century, Poliziano dwells on the divine origin of poetry, as Boccaccio had done in his _Vita di Dante_; and then, after the manner of Horace, he describes its ennobling influence on man, and its general influence on the progress of civilization.[23] He then proceeds to survey the progress of poetry from the most ancient times, and in so doing may be said to have written the first modern history of literature. The second section of the _Sylvae_ discusses the bucolic poets; the third contains that glorification of Virgil which began during the Middle Ages, and, continued by Vida and others, became in Scaliger literary deification; and the last section is devoted to Homer, who is considered as the great teacher of wisdom, and the wisest of the ancients. Nowhere does Poliziano exhibit any appreciation of the aesthetic value of poetry, but his enthusiasm for the great poets, and indeed for all forms of ancient culture, is unmistakable, and combined with his immense erudition marks him as a representative poet of humanism.[24]