Waste Quotes - page 15
The zealous care with which J. M. W. Turner endeavoured to do his duty, is proved by a large existing series of drawings, exquisitely tinted, and often completely coloured, all by his own hand, of the most difficult perspective subjects-illustrating not only directions of line, but effects of light - with a care and completion which would put the work of any ordinary teacher to utter shame. In teaching generally - he would neither waste time nor spare it - he would look over a student's drawing at the Academy, point to a defective part, make a scratch on the paper at the side, say nothing. If the student saw what was wanted, and did it, Turner was delighted; but if the student could not follow. Turner left him.
John Ruskin