When you have clearly and distinctly learned in what good colouring
consists, you cannot do better than have recourse to nature herself, who
is always at hand, and in comparison of whose true splendour the best
coloured pictures are but faint and feeble.
However, as the practice of copying is not entirely to be excluded,
since the mechanical practice of painting is learned in some measure by
it, let those choice parts only be selected which have recommended the
work to notice. If its excellence consists in its general effect, it
would be proper to make slight sketches of the machinery and general
management of the picture. Those sketches should be kept always by you
for the regulation of your style. Instead of copying the touches of
those great masters, copy only their conceptions. Instead of treading in
their footsteps, endeavour only to keep the same road. Labour to invent
on their general principles and way of thinking. Possess yourself with
their spirit. Consider with yourself how a Michael Angelo or a Raffaelle
would have treated this subject; and work yourself into a belief that
your picture is to be seen and criticised by them when completed. Even
an attempt of this kind will rouse your powers.
_Reynolds._