From each according to his abilities: the role of effort in a moral society.
D000124:Achievement; D002648:Child; D002657:Child Development; D002675:Child, Preschool; D003071:Cognition; D003148:Communism; D006801:Humans; D007600:Judgment; D009014:Morals; D011582:Psychological Theory; D012919:Social Behavior