King Yayati, an ancestor of the Kuru dynasty that would eventually produce both the Pandavas and Kauravas, married Devayani, daughter of the sage Shukracharya, but also carried on a relationship with her companion Sharmishtha, a princess who had become Devayani’s attendant after a dispute between their fathers. When Devayani discovered the affair and the children born from it, she appealed to her father in fury.
A curse for infidelity
Shukracharya, protective of his daughter’s honor, cursed Yayati with premature and total old age – decrepitude arriving instantly and completely, stripping him of the vigor, desire, and physical capability he had abused through his infidelity, well before old age would naturally have come to him. Yayati, still deeply attached to worldly pleasure and unwilling to accept the curse’s full weight, begged for some way to delay it, and Shukracharya, unable to revoke the curse outright, allowed one modification: Yayati could transfer his old age temporarily to anyone willing to exchange their own youth for it.
A father asks each son in turn
Yayati approached each of his five sons – four by Devayani and Sharmishtha, and one adopted – asking whether any would take on his old age so that he might continue enjoying youth for a while longer. Four of his sons refused outright, unwilling to sacrifice their own vigor and years for their father’s continued indulgence, regardless of filial duty. Only Puru, the youngest, agreed without hesitation, accepting his father’s decrepitude and giving up his own youth in exchange.
A pleasure that never actually satisfied him
Yayati spent what the Puranas describe as a full thousand years enjoying restored youth and every worldly pleasure available to him, only to eventually reach a stark realization: that desire itself was insatiable by nature, growing rather than diminishing with each indulgence, and that no amount of borrowed time would ever bring him to a point of genuine contentment. Having understood this fully, he returned Puru’s youth to him, reclaimed his own old age, and retired to the forest to pursue spiritual liberation instead – a conclusion reached only after a millennium spent proving the point through direct, exhaustive experience rather than accepting it as abstract wisdom.
A throne earned by sacrifice rather than birth order
Because Puru alone had been willing to make the sacrifice his father asked of him, Yayati passed over his other sons and named Puru his successor, founding the Puru dynasty from which the later Kuru line – and therefore the entire cast of the Mahabharata – would eventually descend. The kingdom’s ultimate inheritance, in this account, traces back not to birth order or ambition, but to a single act of a son giving up his own youth for a father who, by his own later admission, hadn’t deserved the gift nearly as much as he’d wanted it.