his paintings at from five hundred to six hundred; others quote
twelve hundred as authentic. These exaggerated estimates only prove how
extremely popular his designs became and the great number of pictures
ordered from them, some of which no doubt had the advantage of being
touched by his hand, while all in some way or other bear his mental
impress.

Moreover, the great masters frequently changed their methods and styles,
so that one might be mistaken for another, and at times studied and
copied each other. Andrea del Sarto's copy of Raphael's Leo Tenth passed
undetected even by Giulio Romano, who had himself worked on the latter.
Rubens and Velasquez imitated and copied the great Italian masters,
particularly Paul Veronese and Titian; the Caracci and their followers
multiplied Correggios, Raphaels, and the chief Venetians; Girolamo da
Carpi of Ferrara the same; and all with a degree of success that has
greatly perplexed later generations: their own works, in turn, as they
became popular, experiencing from subsequent artists the same process of
multiplication. Of the celebrated Madonna of Loreto there are not fewer
than ten rival claimants for authenticity; while sketches, studies, and
works not directly imitated from, but partaking of the character of
great artists, and often clever enough to be confounded with their
undoubted works, are not rare. Portraits, being direct studies from
Nature, are difficult to decide upon. Hence it is that criticism is so
variable in its decisions.

Beside the above sources of perplexity, it encounters another obstacle
from the restorations pictures have undergone. Injured by time or
obscured by repeated varnishings, they often require some degree of
cleaning to make them intelligible. Unfortunately, in most instances,
the process is sheer assassination. Many of the best works of public
galleries have been subjected to scrubbings more analogous to the labors
of a washtub than to the delicate and scientific treatment requisite to
preserve intact the virgin surface of the painting. Mechanical operators
have passed over them with as little remorse as locusts blight fields
of grain. Their rude hands in numberless instances have skinned the
pictures, obliterating those peerless tints, lights, and shadows, and
those delicate but emphatic touches that bespeak the master-stroke,
leaving instead cold, blank, hard surfaces and outlines, opaque shadows
and crude coloring, out of tone, and in conse