Thus the highest beauty of form must be taken from nature; but it is an
art of long deduction and great experience to know how to find it.

We must not content ourselves with merely admiring and relishing; we must
enter into the principles on which the work is wrought; these do not swim
on the superficies, and consequently are not open to superficial
observers.

Art in its perfection is not ostentatious; it lies hid, and works its
effect itself unseen. It is the proper study and labour of an artist to
uncover and find out the latent cause of conspicuous beauties, and from
thence form principles for his own conduct; such an examination is a
continual exertion of the mind, as great, perhaps, as that of the artist
whose works he is thus studying.

The sagacious imitator not only remarks what distinguishes the different
manner or genius of each master; he enters into the contrivance in the
composition, how the masses of lights are disposed, the means by which
the effect is produced, how artfully some parts are lost in the ground,
others boldly relieved, and how all these are mutually altered and
interchanged according to the reason and scheme of the work. He admires
not the harmony of colouring alone, but he examines by what artifice one
colour is a foil to its neighbour. He looks close into the tints, of
what colours they are composed, till he has formed clear and distinct
ideas, and has learnt to see in what harmony and good colouring consists.
What is learnt in this manner from the works of others becomes really our
own, sinks deep, and is never forgotten; nay, it is by seizing on this
clue that we proceed forward, and get further and further in enlarging
the principle and improving the practice.