"Once bitten, twice shy."--This story was told by the Master when at Jetavana, about subduing desires.
We are told that some five hundred rich friends, sons of merchants of Sāvatthi, were led by listening to the Master's teachings to give their hearts to the Truth, and that joining the Brotherhood they lived in Jetavana in the part that Anātha-piṇḍika paved with gold pieces laid side by side 1.
Now in the middle of a certain night thoughts of lust took hold of them, and, in their distress, they set themselves to lay hold once again of the lusts they had renounced. In that hour the Master raised aloft the lamp of his omniscience to discover what manner of passion had hold of the Brethren in Jetavana, and, reading their hearts, perceived that lust and desire had sprung up within them. Like as a mother watches over her only child, or as a one-eyed man is careful of the one eye left him, even so watchful is the Master over his disciples;--at morn or even, at whatsoever hour their passions war against them, he will not let his faithful be overpowered but in that self-same hour subdues the raging lusts that beset them. Wherefore the thought came to him, "This is like as when thieves break into the city of an emperor; I will unfold the Truth straightway to these Brethren, to the end that, subduing their lusts, I may raise them to Arahatship."
So he came forth from his perfumed chamber, and in sweet tones called by name for the venerable Elder, Ānanda, Treasurer of the Faith. And the Elder came and with due obeisance stood before the Master to know his pleasure. Then the Master bade him assemble together in his perfumed chamber all the Brethren who dwelt in that quarter of Jetavana. Tradition says that the Master's thought was that if he summoned only those five hundred Brethren, they would conclude that he was aware of their lustful mood, and would be debarred by their agitation from receiving the Truth; accordingly he summoned all the Brethren who dwelt there. And the Elder took a key and went from cell to cell summoning the Brethren till all were assembled in the perfumed chamber. Then he made ready the Buddha-seat. In stately dignity like Mount Sineru resting on the solid earth, the Master seated himself on the Buddha-seat, making a glory shine round him of paired garlands upon garlands of six-coloured light, which divided and divided into masses of the size of a platter, of the size of a canopy, and of the size of a tower, until, like shafts of lightning, the rays reached to the heavens above. It was even as when the sun rises, stirring the ocean to the depths.
With reverent obeisance and reverent hearts, the Brethren entered and took their seats around him, encompassing him as it were within an orange curtain. Then in tones as of Mahā-Brahma the Master  said, "Brethren, a Brother should not harbour the three evil thoughts,--lust, hatred and cruelty. Never let it be imagined that wicked desires are a trivial matter. For such desires are like an enemy; and an enemy is no trivial matter, but, given opportunity, works only destruction. Even so a desire, though small at its first arising, has only to be allowed to grow, in order to work utter destruction. Desire is like poison in food, like the itch in the skin, like a viper, like the thunderbolt of Indra, ever to be shunned, ever to be feared. Whensoever desire arises, forthwith, without
finding a moment's harbourage in the heart, it should be expelled by thought and reflection,--like as a raindrop rolls at once off the leaf of the lotus. The wise of former times so hated even a slight desire that they crushed it out before it could grow larger." And so saying, he told this story of the past.
Once on a time when Brahmadatta was reigning in Benares, the Bodhisatta was re-born into life as a jackal and dwelt in the forest by the river-side. Now an old elephant died by the banks of the Ganges, and the jackal, finding the carcass, congratulated himself on lighting upon such a store of meat. First he bit the trunk, but that was like biting a plough-handle. "There's no eating here," said the jackal and took a bite at a tusk. But that was like biting bones. Then he tried an ear, but that was like chewing the rim of a winnowing-basket. So he fell to on the stomach, but found it as tough as a grain-basket. The feet were no better, for they were like a mortar. Next he tried the tail, but that was like the pestle. "That won't do either," said the jackal; and having failed elsewhere to find a toothsome part, he tried the rear and found that like eating a soft cake. "At last," said he, "I've found the right place," and ate his way right into the belly, where he made a plenteous meal off the kidneys, heart and the rest, quenching his thirst with the blood. And when night came on, he lay down inside. As he lay there, the thought came into the jackal's mind, "This carcass is both meat and house to me, and wherefore should I leave it?" So there he stopped, and dwelt in the elephant's inwards, eating away. Time wore on till the summer sun and the summer winds dried and shrank the elephant's hide,  until the entrance by which the jackal had got in was closed and the interior was in utter darkness. Thus the jackal was, as it were, cut off from the world and confined in the interspace between the worlds. After the hide, the flesh dried up and the blood was exhausted. In a frenzy of despair, he rushed to and fro beating against his prison walls in the fruitless endeavour to escape. But as he bobbed up and down inside like a ball of rice in a boiling saucepan, soon a tempest broke and the downpour moistened the shell of the carcass and restored it to its former state, till light shone like a star through the way by which the jackal had got in. "Saved! saved!" cried the jackal, and, backing into the elephant's head made a rush head-first at the outlet. He managed to get through, it is true, but only by leaving all his hair on the way. And first he ran, then he halted, and then sat down and surveyed his hairless body, now smooth as a palm-stem. "Ah!" he exclaimed, "this misfortune has befallen me because of my greed and my greed alone. Henceforth I will not be greedy nor ever again get into
the carcass of an elephant." And his terror found expression in this stanza:--
And with these words the jackal made off, nor did he ever again so much as look either at that or at any other elephant's carcass. And thenceforth he was never greedy again.
His lesson ended, the Master said, "Brethren, never let desires take root in the heart but pluck them out wheresoever they spring up."  Having preached the Four Truths (at the close whereof those five hundred Brethren won Arahatship and the rest won varying lesser degrees of salvation), the Master identified the Birth as follows: "I was myself the jackal of those days."
314:1 Or 'paved with crores.' See Vinaya, Cullav. vi. 4. 9, translated in S. B. E., Volume XX., page 188. Cf. also Jātaka (text) I. 92.