If you follow the course of one man through constant practice, your intelligence would have to be crude indeed for you not to get some nourishment from it.
Cennino CenniniIn the first place you must study drawing for at least one year; then you must remain with a master at the workshop for the space of six years at least , that you may learn all the parts and members of the art...drawing without intermission on holidays and work-days
Cennino Cennini