Pope, like Mandeville, founds virtue upon vice. The ruling passion is evil, but reason gives it a bias towards good.[844] "Spleen, obstinacy, hate, and fear," each produce "crops of wit and honesty;" "anger" is the parent of "zeal and fortitude;" "avarice" of "prudence;" "sloth" of "philosophy;" and every virtue under heaven may issue from "pride or shame."[845] The ruling passion having engulphed the whole family of affections and desires, this individual is a personification of anger, that individual of hate; a third of fear; a fourth of sloth; a fifth of pride. The sole moving principle of man is his giant passion.[846] The function of reason is only to foster it,[847] and select the means for its gratification. Whatever these means may be, the motive of the incarnate monster lust, is to feed sensuality; of the monster sloth to secure ease; of the monster pride to inflate self-importance. "The same ambition," says Pope, "may make a patriot, as it makes a knave."[848] But the incarnation of an all-pervading ambition can be only a patriot in appearance, and uses patriotism to serve the ends of ambition. Let the two diverge, and by the law of his nature he must fling the patriotism to the winds. "Either," says our Lord, "make the tree good, and his fruit good; or else, make the tree corrupt and his fruit corrupt."[849] On Pope's theory, to make the tree good is impossible. Man has no escape from the ruling passion he brings into the world. He must be angry, avaricious, or slothful, according to the seed which was sown in him at his birth, and the tree must remain corrupt to the last.