I am glad you encouraged me with the 'Stoke' [his painting 'Stoke-by-Nayland', circa 1835] What say you to a summer morning? July or August, at eight or nine o'clock, after a slight shower during the night, to enhance the dews in the shadowed part of the picture, under 'Hedge row elms and hillocks green.' Then the plough, cart, horse, gate, cows, donkey, &c. are all good paintable material for the foreground, and the size of the canvas sufficient to try one's strength, and keep one at full collar.
"Constable". Book by Leslie Parris and Ian Fleming-Williams, Tate Gallery Publications, London, p. 380, Letter to William Purton (6 February 1836), 1993.