In the 19th century, Lisco and Fairbairn stated that in the parables of Jesus, "the image borrowed from the visible world is accompanied by a truth from the invisible (spiritual) world" and that the parables of Jesus are not "mere similitudes which serve the purpose of illustration, but are internal analogies where nature becomes a witness for the spiritual world". Similarly, in the 20th century, calling a parable "an earthly story with a heavenly meaning", William Barclay states that the parables of Jesus use familiar examples to lead men's minds towards heavenly concepts. He suggests that Jesus did not form his parables merely as analogies but based on an "inward affinity between the natural and the spiritual order."