Masolino's contribution to the whole appears to be confined to three pictures: St. Peter preaching, with Carmelites in the background to carry his doctrines into fifteenth century Florence, on the left of the window; the upper row of scenes on the right wall, representing St. Peter and St. John raising the cripple at the Beautiful Gate of the Temple, and the healing of Tabitha (according to others, the resuscitation of Petronilla); and the narrow fresco of the Fall of Adam and Eve, on the right of the entrance. Some have also ascribed to him the striking figure of St. Peter enthroned, attended by Carmelites, while the faithful approach to kiss his feet--the picture in the corner on the left which, in a way, sets the keynote to the whole--but it is more probably the work of Masaccio (others ascribe it to Filippino). Admirable though these paintings are, they exhibit a certain immaturity as contrasted with those by Masaccio: in the Raising of Tabitha, for instance, those two youths with their odd headgear might almost have stepped out of some Giottesque fresco; and the rendering of the nude in the Adam and Eve, though wonderful at that epoch, is much inferior to Masaccio's opposite. Nevertheless, Masolino's grave and dignified figures introduced the type that Masaccio was soon to render perfect. From the hand of Masaccio are the Expulsion from Paradise; the Tribute Money; the Raising of the Dead Youth (in part); and (probably) the St. Peter enthroned, on the left wall; St. Peter and St. John healing the sick with their shadow, under Masolino's Peter preaching (and the figure behind with a red cap, leaning on a stick, is Masaccio's pious portrait of his master Masolino himself); St. Peter baptising, St. Peter and St. John giving alms, on the opposite side of the window. Each figure is admirably rendered, its character perfectly realised; Masaccio may indeed be said to have completed what Giotto had begun, and freed Italian art from the mannerism of the later followers of Giotto, even as Giotto himself had delivered her from Byzantine formalism. "After Giotto," writes Leonardo da Vinci, "the art of painting declined again, because every one imitated the pictures that were already done; thus it went on from century to century until Tommaso of Florence, nicknamed Masaccio, showed by his perfect works how those who take for their standard any one but Nature--the mistress of all masters--weary themselves in vain."[54] This return to nature is seen even in the landscape, notably in the noble background to the Tribute Money; but above all, in his study of man and the human form. "For the first time," says Kugler, "his aim is the study of form for itself, the study of the external conformation of man. With such an aim is identified a feeling which, in beauty, sees and preserves the expression of proportion; and in repose or motion, the expression of an harmonious development of the powers of the human frame." For sheer