This light and darkness in our chaos joined, What shall divide? The God within the mind. Extremes in nature equal ends produce, In man they join to some mysterious use; Though each by turns the other’s bound invade, As, in some well-wrought picture, light and shade, And oft so mix, the difference is too nice Where ends the virtue or begins the vice. Fools! who from hence into the notion fall, That vice or virtue there is none at all. If white and black blend, soften, and unite A thousand ways, is there no black or white? Ask your own heart, and nothing is so plain; ’Tis to mistake them, costs the time and pain.