The story on legacy is based on King Indradyumna and turtle
and is from the Vana Parva of Mahabharata.
Due to his good karma, King Indradyumna had gone to heaven. After
many centuries in heaven, he was cast out and told that he could return only if
people on earth still recalled his good deeds.
The king first went to Sage Markandeya who had lived longer
than most humans. Sage Markandeya did not remember him and asked him to meet an
owl who had lived longer than him.
The owl did not remember the king but asked him to meet a
stork who might be able to recollect him.
The stork was not able to remember him but informed him
about a turtle named Akupara, who had outlived almost all living beings on earth.
Akupara, the turtle, remembered King Indradyumna as the king
who had built the lake in which he lived.
But the King did not remember about ever digging the lake.
The turtle explained that though he had not had the lake
dug, it existed as a result of his generosity.
During his reign, the king had given away many cows. These
cows had kicked up so much dusts while leaving their sheds that they had
created a depression that turned into a lake following the rains.
That lake later became home to many fishes and turtles. Birds
and animals drank water from the lake throughout the year. Thus, King
Indradyumna could never be forgotten – there were many on earth who had
benefited from his actions. Thus, an old, forgotten deed allowed Indradyumna
to regain his place in heaven and live among gods once again.