[210] He was dwelling at Sāvatthī. … There the Blessed One … "Bhikkhus, suppose there were a great tree. All its roots — both those that go downwards and those that spread sideways — draw the sap upwards. Indeed, bhikkhus, sustained by that nutriment, fuelled by that, that great tree would stand for a long time, for a long stretch of time. In just the same way, bhikkhus, in one who dwells contemplating gratification (assāda) in things subject to clinging, craving (taṇhā) increases. With craving as condition, clinging (upādāna) … Such is the origin of this whole mass of suffering (dukkha)."
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.