..Turner did not believe that colour was reducible to system; and Gainsborough, when painting his 'Blue Boy', seems to have been of the same opinion. I think it was the remark of Mr. Field, when we were looking at that celebrated picture [ Blue Boy ], that Gainsborough's eye was truer than his head, since against his theory he had introduced a sufficiency of warm colours into the flesh tints to balance the predominating cold of the picture.