The parable of the tares describes how the Son of man sowed good seed (children of the kingdom) in the world, but the devil came and sowed weeds (children of the wicked one) among the wheat while men slept. Both were allowed to grow together until the harvest, at which point the angels would gather the weeds first to be burned and the wheat to be saved. Similarly, the kingdom of heaven starts small like a mustard seed but grows into a large tree where birds come to lodge, representing how evil spirits come into the kingdom of Antichrist.