Jealousy is a disease, love is a healthy condition. The immature mind often mistakes one for the other, or assumes that the greater the love, the greater the jealousy — in fact, they are almost incompatible; one emotion hardly leaves room for the other.

Robert Anson Heinlein, "Stranger in a Strange Land"

Of all the passions, jealousy is that which exacts the hardest service and pays the bitterest wages. Its service is to watch the success of our enemies; its wages to be sure of it.

Charles Caleb Colton, "Lacon"

Jealousy does not wait for reasons.

Mahatma Gandhi, "An Autobiography or The Story of My Experiments with Truth"

Jealousy feeds upon suspicion, and it turns into fury or it ends as soon as we pass from suspicion into certainty.

Francois de La Rochefoucauld, "Reflections; or Sentences and Moral Maxims"

Jealousy is always born with love, but does not always die with it.

Francois de La Rochefoucauld, "Reflections; or Sentences and Moral Maxims"

There is more self-love than love in jealousy.

Francois de La Rochefoucauld, "Reflections; or Sentences and Moral Maxims"

Set me as a seal upon thine heart, as a seal upon thine arm: for love is strong as death; jealousy is cruel as the grave: the coals thereof are coals of fire, which hath a most vehement flame.

Solomon, "Song of Solomon 8:6"