The Dead Live Inside of Us

Just as we affect others merely by being alive, those who are already gone continue to affect the living. A person lives on, even after returning to dust and ashes, as long as someone still clearly remembers the things he did, the things he said, his ways, his sensitivities, the thoughts that were his alone. As those who knew him pass on in their turn, the posterity in which he survives then shrinks until the last of them is gone, and he dies a second, final death. Thereafter he appears no more among the living.
However, this extended life, depending entirely on the memory of the living, is always in peril. So the living must continually renew their memory of the dead and share their life with them. They must accept as their natural duty not only to mourn the dead, but also to try to call back the life that the dead have lost. They must be like Orpheus, the musician, who followed his wife Eurydice, dead of snakebite, all the way down to the realm of death.
 --Takehiko Fukunaga, Flowers of Grass