- Shakespeare's personification of jealousy in Othello:O! beware my lord, of jealousy;It is the green-ey'd monster which doth mockThe meat it feeds on.Othello (III, iii)
The phrase is probably based upon an analogy between jealousyand jaundice - a disease that causes a yellowy-greenish tingein the whites of the eyes. Just as sufferers from jaundice were supposed(erroneously) to see everything tinged yellow or green, so those afflictedwith irrational jealousy are presumed to find evidence of their suspicionsin everything they look upon.
The Dublin actor Thomas Layfield (fl. 1750) once broughta performance of Othello to a sudden halt by declaiming:O! beware my lord, of jealousy;It is a green-eyed lobster.
This was the first sign of the madness that led to his spendinghis last years in a Dublin asylum.