Jealousy is malarial because:
It recurs.
It is unpredictable in both frequency and ferocity.
It causes you to hallucinate.
Nothing you think or predict or imagine, no conclusion you reach in a condition of jealousy, can be trusted. Jealousy builds a housing project of logic from a single brick. What can you do? Wander the ramps and serviceways of your private Broadwater Farm like any other puzzled debt collector. Every floor looks the same. Knock on the right door and there is a sudden tense silence inside. You want something from the occupant, but you no longer understand what it is, let alone how to get it.
- M. John Harrison, Signs of Life, p.211