To paint Achilles the most goodly of men, though you had for your model the most abject you must depend on him, and can depend on him for the structure of the human body, for its movement and poise. The proof of this is that Raphael used his pupils in his studies for the movements of the figures in his divine pictures.
Whatever your talents may be, if you paint not from your studies after nature, but directly from the model, you will always be a slave and your pictures will show it. Raphael, on the contrary, had so completely mastered nature and had his mind so full of her, that instead of being ruled by her, one might say that she obeyed him and came at his command to place herself in his pictures.
Ingres.
LIII
No one can ever design till he has learned the language of Art by making many finished copies both of Nature, Art, and of whatever comes in his way, from
earliest childhood. The difference between a bad artist and a good is, that the bad artist seems to copy a great deal, the good one does copy a great deal.
Blake.
LIV