"Who to the life an exact Piece would make,
Must not from others Work a Copy take;
No, not from Rubens or Vandike.
Much less content himself to make it like
Th' Ideas and the Images which ly
In his own Fancy, or his Memory.
No, he before his sight must place
The Natural and Living Face:
The real Object must command
Each judgment of his Eye, and Motion of his Hand.
(Abraham Cowley, ode prefácio da History of the Royal Society, de Thomas Sprat)