206 DEVELOPMENT AND PURPOSE CHAP. 



lines, partly no doubt in occult underlying sympathy with 

 others, but also very largely in overt and strenuous 

 antagonism, so does each human community live its own 

 life, flourish and grow through the internal conditions that 

 make it strong, decay and die as often by internal dissolu- 

 tion as by the weight of external force. True, there is 

 always, or almost always, a contact with other communities 

 which is not merely hostile, and the growth of civilisation 

 in particular is forwarded, one might almost say measured, 

 by the development of such contact and the substitution 

 of the peaceful penetration of culture for the internecine 

 war of barbarism. Human history grows towards a unity, 

 but it is founded on diversity, and down to the present day 

 its growth is still to be traced in numerous independent 

 centres of evolution. Now this independence does not 

 wholly destroy the continuity of history. We ourselves 

 owe our civilisation not to the barbarians of the Teutonic 

 forest, but to Roman, Greek and Jew from whom they 

 learnt. There is a thread of continuity running through 

 all historic culture, but it is crossed and recrossed by many 

 another thread, and the result is at first sight a tangle rather 

 than a neatly woven tissue of clear pattern. 



In this tangle we may find a clue if we can seize some 

 distinctive feature of our own civilisation, the latest in 

 time, and therefore the net result of the whole movement 

 up to the present. One such feature has been already 

 mentioned. It is the development of knowledge, a 

 development which is not, indeed, continuous, but which 

 for a simple reason, which I will refer to later, proceeds on 

 the whole more surely and more regularly than any other 

 collective effort of mankind. With knowledge we may 

 rank the control of physical conditions as its immediate 

 result so immediate, indeed, as in the absence of written 

 records to be a sufficient measure of the degree of know- 

 ledge actually attained by a people. Now if we take know- 

 ledge and the material arts as a provisional basis of classi- 

 fication, and with this in our minds survey the field 

 described above, we find a vast range of variation presented 

 by peoples still inhabiting the earth. Without going back- 

 ward in time we can pass from our own aeroplanes and wire- 



