Dead bury dead

What does the phrase mean: "Let the dead bury their dead?"

Jesus, with his disciples, was on a preaching journey, sometimes urging people to drop everything and "Follow me." One man said he would follow Jesus, but first wished to bury his father. Jesus said, "Let the dead bury their dead." Essentially, let the past go, start your new life today. See Luke 9: 59-62. SS