LIKE A MIRAGE IS THIS BODY
Phenupamam kayamimam viditva marici dhammam abhisambudhano
Chetvana marassa papupphakani adassanam maccu rajassa gacche
On one occasion, when the Buddha was residing in Jetavana monastery at Savatthi, a certain bhikkhu after obtaining a subject of meditation from the Buddha went to the forest for the purpose of practicing meditation.
On the way he saw a mirage. Reflecting mindfully within himself, he realised that a mirage was after all only an illusion of a sheet of water; so also was his body an illusion and insubstantial by reason of birth and decay. Fixing his mind on the mirage, he continued with his meditation practice.
Later, he went for a bath near the bank of the river Aciravati. While resting under a tree close to the river, and seeing the froth breaking up, he realised further the impermanent nature of the body.
From the Jetavana monastery, the Buddha saw the bhikkhu, sent forth his radiance and exhorted him, 'Bhikkhu, you are on the right track. Keep it up. It is good that you have realised that the body is impermanent like froth and insubstantial like a mirage.' At the conclusion of the exhortation, the bhikkhu attained Arahanthood.