Paolo was summoned to Padua by Donato, when the latter was working there, and at the entrance of the house of the Vitali he painted some giants in terra-verde, which, as I have found in a Latin letter written by Girolamo Campagnola to Messer Leonico Tomeo, the philosopher, are so beautiful that Andrea Mantegna held them in very great account. Paolo wrought in fresco the Volta de' Peruzzi, with triangular sections in perspective, and in the angles of the corners he painted the four elements, making for each an appropriate animal--for the earth a mole, for the water a fish, for the fire a salamander, and for the air a chameleon, which lives on it and assumes any colour. And because he had never seen a chameleon, he painted a camel, which is opening its mouth and swallowing air, and therewith filling its belly; and great, indeed, was his simplicity in making allusion by means of the name of the camel to an animal that is like a little dry lizard, and in representing it by a great uncouth beast. [Illustration: PORTRAITS (_After the panel by_ Paolo Uccello. _Paris: Louvre, 1272_) _Mansell_] Truly great were the labours of Paolo in painting, for he drew so much that he left to his relatives, as I have learnt from their own lips, whole chests full of drawings. But, although it is a good thing to draw, it is nevertheless better to make complete pictures, seeing that pictures have longer life than drawings. In our book of drawings there are many figures, studies in perspective, birds, and animals, beautiful to a marvel, but the best of all is a mazzocchio drawn only with lines, so beautiful that nothing save the patience of Paolo could have executed it. Paolo, although he was an eccentric person, loved talent in his fellow-craftsmen, and in order that some memory of them might go down to posterity, he painted five distinguished men with his own hand on a long panel, which he kept in his house in memory of them. One was Giotto, the painter, standing for the light and origin of art; the second was Filippo di Ser Brunellesco, for architecture; Donatello, for sculpture; himself, for perspective and animals; and, for mathematics, Giovanni Manetti, his friend, with whom he often conferred and discoursed on the problems of Euclid.