And as with age his body uglier grows, / So his mind cankers.

--- Prospero, The Tempest, Act IV, Scene 1. The epigraph to William Ian Miller's Losing It  (2001)

Quote in context, referring to (?) Caliban:

Prospero: A devil, a born devil, on whose nature
Nurture can never stick; on whom my pains,
Humanely taken, all, all lost, quite lost,
And, as with age his body uglier grows,
So his mind cankers. . . .