Note to Macbeth, Act 4, Scene 3, line 63:
"cistern of my lust"
"
Shakespeare uses the word "cistern" in the sense of a "pond," or a "natural reservoir." Furthermore, he associates it with repulsive creatures. In Antony and Cleopatra the creatures are "scal'd snakes"; in Othello a cistern is a place where "foul toads ... knot and gender."