One question remains, and a most perplexing one. How can one distinguish between a group mind and a group purpose, or the accidental coincidence of many minds and many purposes? A flock of migrating birds has no group mind—each bird would travel south at the same time and the same rate of speed, were there no flock at all. Or still lower forms, such as unicellular organisms, may move simultaneously to warmer waters. On the other extreme, the hordes of Huns led by Attila had a group purpose in their migration; the leader gave the word, and the followers leaped together to their horses’ backs to ride from Asia into Europe. But when a half million negroes migrate from the southern to the northern states in a few years, coming family by family, as the opportunity affords, yet with a steady tendency of drift, is that a group mind or the accidental agreement of many individuals? Is it mind or minds? And the same problem is present in a declaration of war, or the victory of a foot-ball team, or the adoption of a new fashion of clothes. When does the group act and when the individual members? When do we have the mind of all, when the mind of each? To this crucial problem I must present one qualification and one answer. The qualification is: the group never acts except through its constituent individuals, any more than the mind acts without its brain cells and bodily organs. The difference between the act of all and the act of each is not a complete disjunction but a difference of emphasis, of interpretation, of purpose. When the army marches, every soldier goes ahead; when the nation elects its president, the millions of voters cast their ballots; when the church adopts a creed or reforms its ritual, the many believers experience a change in their faith and their hope. Not that group opinion need be unanimous; it is rather a mode of general consent by which unified action can arise out of conflicting opinions, by which many individuals are absorbed into a group mind. Thus in many, perhaps in most cases we cannot say definitely: this is group mind, not personal preference, or this is individual action, and the group has nothing to do with it. The problem is much like that which faced Kant in defining moral action, when the demands of the universal law may often coincide with personal preference, perhaps even with the greatest and most appealing happiness.