I paint a window, just as I look through a window.  If this window when open doesn't look good in my picture, I draw a curtain and close it as I would have done in my room.  One must act in painting, as in life, directly.  Admittedly painting has its conventions, of which it is necessary to take account, since one can't do otherwise.  For this reason one must have constantly before one's eyes the very presence of life.     

- Picasso