. These doors open and
shut: they were meant to do so, especially to shut. Ghiberti's second
pair of doors for the Baptistery do not _shut_: they are closed, but
they do not give the sense of shutting anything in or keeping anything
out. They are more like windows than doors. They give no impression of
defence or resistance: they are doors in nothing but name, and the
chance that they hang on hinges. Were it merely a contest between
Ghiberti and Donatello as to which sculptor were the more skilled
constructor of doors, further comment would be unprofitable; but it
raises the wider question of the laws and limitations of
bas-relief--the application to sculpture of the principles of
painting; in short, the broad line of demarcation between two
different arts. Michael Angelo probably realised the unity of the arts
better than Donatello, but Donatello knew enough to treat sculpture
with due respect: he valued it too highly to confuse the issue by
pictorial embellishments. It is no question of a convention, still
less of a canon. But there are inherent boundaries between the two
arts; and where the boundaries are overstepped, one or the other art
must lose some of its essential quality and charm. Donatello's reliefs
at Padua are crowded: Ghiberti's (on the second gates) are
overcrowded. The difference in degree produces a difference in
principle. If Ghiberti had made pictures instead of reliefs, the
atmosphere would keep the objects in their right places, while
differences of colour would give distinction to certain parts and the
chief figures would still predominate. In other reliefs Ghiberti
lavished so much care on landscape and architecture that the figures
become of secondary importance: on one relief a tree casts its shadow
on a cloud.[172] Ghiberti, in fact, with all his plastic elegance,
with a grace, suavity and sense of beauty which Donatello never
approached, was a painter at heart. "_L'animo mio alla pittura era in
grande parte volto_," he says in his Commentary,[173] and the faults
of his sculpture are due to this versatility. Donatello only used his
pictorial knowledge to perfect form and feature; and, complex as his
architectural backgrounds often are, they never suggest experiments in
perspective, and they never detract from the primacy of the people and
the incident. Michael Angelo was under no illusion on this point: he
never confused painting and sculpture. Yet he said Ghiberti's gates
would be worthy port