Desperate Need for Love
In the oasis complex, the thirsty man images he sees water, palm trees, and shade not because he has evidence for the belief, but because he has a need for it. Desperate needs bring about a hallucination of their solution: thirst hallucinates water, the need for love hallucinates a prince or princess. The oasis complex is never a complete delusion: the man in the desert does see something on the horizon. It is just that the palms have withered, the well is dry, and the place is infected with locusts.
Alain de Botton, in 'On Love'