Those who, either from their own engagements and hurry of business, or
from indolence, or from conceit and vanity, have neglected looking out of
themselves, as far as my experience and observation reaches, have from
that time not only ceased to advance and improve in their performance,
but have gone backward. They may be compared to men who have lived upon
their principal till they are reduced to beggary and left without
resources.

I can recommend nothing better, therefore, than that you endeavour to
infuse into your works what you learn from the contemplation of the works
of others. To recommend this has the appearance of needless and
superfluous advice, but it has fallen within my own knowledge that
artists, though they are not wanting in a sincere love for their art,
though they have great pleasure in seeing good pictures, and are well
skilled to distinguish what is excellent or defective in them, yet go on
in their own manner, without any endeavour to give a little of those
beauties which they admire in others, to their own works. It is
difficult to conceive how the present Italian painters, who live in the
midst of the treasures of art, should be contented with their own style.
They proceed in their common-place inventions, and never think it worth
while to visit the works of those great artists with which they are
surrounded.

I remember several years ago to have conversed at Rome with an artist of
great fame throughout Europe; he was not without a considerable degree of
abilities, but those abilities were by no means equal to his own opinion
of them. From the reputation he had acquired he too fondly concluded
that he stood in the same rank, when compared to his predecessors, as he
held with regard to his miserable contemporary rivals.