It may be said that the literary and artistic doctrines and opinions of the Middle Ages have, with few exceptions, a value rather for the history of culture than for the general history of science. The like observation holds good of the Renaissance, for here, too, the circle of the ideas of antiquity was not overstepped. Culture increases; original sources are studied; the ancient writers are translated and commented upon; many treatises are written and henceforth printed upon poetry and the arts, grammars, rhetorics, dialogues, and dissertations upon the beautiful: the proportions have increased, the world has become bigger; but truly original ideas do not yet show themselves in the domain of æsthetic science. The mystical tradition is refreshed and strengthened by the renewed cult of Plato: Marsilio Ficino, Pico della Mirandola, Cattani, Leon Battista Alberti, in the fifteenth century, and Pietro Bembo, Mario Equicola, Castiglione, Nobili, Betussi, and very many others in the following century, wrote upon the Beautiful and upon Love. Among the most noteworthy productions of the sort, a crossing of the mediæval and classical currents, is the book of the _Dialogues of Love_ (1535), composed in Italian by the Spanish Jew Leo, and translated into all the cultured languages of the time.[11] The three parts into which it is divided treat of the nature and essence, of the universality, and of the origin of love; and it is demonstrated that every beautiful thing is good, but not every good thing is beautiful; that beauty is a grace which dilates the soul and moves it to love, and that knowledge of lesser beauties leads to that of higher spiritual beauties. The author gave the name of "Philography" to these and similar affirmations and effusions of which the book is composed. Equicola's[12] work is also interesting, because it contains historical accounts of those who wrote upon the subject before he did so himself. The same intuition was versified and sighed forth by the Petrarchists in their sonnets and ballads, while others, rebellious and mocking, derided it in comedies, verses in _terza rima_ and parodies of all sorts. Some mathematicians, reincarnations of Pythagoras, set to work to determine beauty by exact relations: for instance Leonardo's friend, Luca Paciolo, in the _De divina proportione_ (1509), in which he laid down the pretended æsthetic law of the golden section.[13] And side by side with these new Pythagoreans were those who revived the canon of Polycletus as to the beauty of the human body, especially of the female body, such as Firenzuola, Franco, Luigini, and Dolce. Michæl Angelo fixed an empirical canon for painting in general, when he stated that the means of giving movement and grace to figures[14] consisted in the observance of a certain arithmetical relation. Others, such as Fulvio Pellegrino Morato, investigated the symbolism or meaning of colours. The Platonists generally placed beauty in the soul, the