text:  It is the nature of the mind under certain impulses and impressions to exaggerate to combine from memory not from sight even to the verge of the impossible; for even this extravagance is the product of human passion which by its nature disdains common boundaries; and this in painting is especially the province of Colour which may be said to be the poetical language of art and admits differences of the same kind as exist between common speech and poetical and figurative diction