PROGRESS, BIOLOGICAL AND OTHER 45 



ness of bodily and mental organization difficult for 

 us to imagine. 



Man passes freely from one aggregation to another. 

 He can change his nation or his city; he can belong 

 to a dozen organizations — biologically speaking, can 

 be aggregated in a dozen different ways — and play 

 a different part as unit in each. He can follow one 

 profession in the morning, another at night, and be a 

 hobby-horse rider in between. 



This plastic mind has endowed him with a new 

 biological possibility. He can do what no other or- 

 ganism can — he can be both specialized and general- 

 ized at one and the same time. 



In biology, the aggregation of units to form units 

 of higher grade has been always followed by division 

 of labour among the units; and this division of la- 

 bour has, in all infrahuman history, been made pos- 

 sible only by an irreversible specialization.^^ A sol- 

 dier-ant is a soldier, and there its possibilities end. 

 It cannot do what the worker or the queen can do. 

 A muscle-cell, because it has gained the power to 

 contract, is cut off from other possibilities; it cannot 

 secrete, or digest, or carry messages. The aggregate 

 of nerve-cells which makes the physical basis of mind 

 is held fixed to its post, incapable of turning to other 

 functions. 



It follows that the units of all such aggregates are 

 subordinate to the whole — they have lost their inde- 

 pendence, and can often no longer be considered as 



11 See Huxley, '12. 



