To appease his Manes. To do when a person is dead what would have pleased him or was due to him when alive. The spirit or ghost of the dead was by the Romans called his Manes, which never slept quietly in the grave so long as survivors left its wishes unfulfilled. The 19th February was the day when all the living sacrificed to the shades of dead relations and friends.
Manes (2 syl.) from the old word manis, i.e. “bonus,” “quod eos venerantes manes vocarent, ut Græci chrestous.” (See Lucretius, iii. 52.) It cannot come from maneo, to remain (because this part of man remains after the body is dead), because thea is long.
In the Christian Church there is an All Souls' Day.