"..Something else about Delacroix — he had a discussion with a friend about the question of working absolutely from nature, and said on that occasion that one should take one's 'studies' from nature — but that the 'actual painting' had to be made 'by heart'. This friend was walking along the boulevard when they had this discussion — which was already fairly heated. When they parted the other man was still not entirely persuaded. After they parted, Delacroix let him stroll on for a bit — then (making a trumpet of his two hands) bellowed after him in the middle of the street — to the consternation of the worthy passers-by: 'By heart! By heart!' ('Par coeur! Par coeur!') I can't tell you how much I enjoyed reading this article and some other things about Delacroix.."
January 1, 1970
https://en.wikiquote.org/wiki/Eug%C3%A8ne_Delacroix