Footnote 23: One of the professors being employed in restoring a piece of Coreggio, analyzed the mode of colouring. Upon the chalk, he said, the artist appeared to have laid a surface of prepared oil, which then received a thick mixture of colours, in which the ingredients were two thirds of oil and one of varnish; that the colours seemed to have been very choice, and particularly purified from all kind of salts, which in progress of time eat and destroy the picture; and that the before-mentioned use of prepared oil must have greatly contributed to this purification by absorbing the saline particles. It was, moreover, his opinion, that Coreggio adopted the method of heating his pictures, either in the sun, or at the fire, in order that the colours might become as it were interfused, and equalized in such a way as to produce the effect of having been poured, rather than laid on. Of that lucid appearance which, though so beautiful, does not reflect objects, and of the solidity of the surface, equal to the Greek pictures, he remarks, that it must have been obtained by some strong varnish unknown to the Flemish painters themselves, who prepared it of equal clearness and liveliness but not of equal strength. See vol. i. p. 49. But his grand and mastering quality, his crowning triumph and distinction above all other artists known to us, is his thorough knowledge of lights and shades. Like nature herself he does not present objects to us with the same force of light, but varied according to the surfaces, oppositions, and distances; it flows in a gradation insensibly increasing and diminishing, a distinction essential in aërial perspective, in which he is so great, and contributing finely to the general harmony. He observed the same principle in his shades, representing the reflection of colour upon each, in so delicate a degree, that though using them so abundantly, his shadows are always varied like nature's, never monotonous. This quality is eminently conspicuous in his night-piece in the Dresden gallery;[24] and in his Magdalen, there seen reposing in a cave; a small picture it is true, but estimated in the purchase at twenty-seven thousand crowns. By the use of his chiaroscuro he not only gave superior softness and rotundity to his forms, but displayed a taste in the whole composition, such as had never been witnessed before. He disposed the masses of his lights and shades with an art, purely natural in its foundation, but in the selection and effect altogether ideal. And he arrived at this degree of perfection by the very same path pursued by Michelangiolo, availing himself of models in clay and wax, the remains of some of which are said to have been found in the cupola at Parma not many years ago. It is also currently reported, that while employed in that city, he engaged the assistance of the famous modeller