Manner is always seductive. It is more or less an imitation of what has
been done already, therefore always plausible. It promises the short
road, the near cut to present fame and emolument, by availing ourselves
of the labours of others. It leads to almost immediate reputation,
because it is the wonder of the ignorant world. It is always accompanied
by certain blandishments, showy and plausible, and which catch the eye.
As manner comes by degrees, and is fostered by success in the world,
flattery, &c., all painters who would be really great should be
perpetually on their guard against it. Nothing but a close and continual
observance of nature can protect them from the danger of becoming
mannerists.
_Constable._