548 ALEXANDER PEDLER LECTURE 



Universe were made expressly for their habitation, scarcely antedating 

 their arrival. By precisely similar reasoning, the only habitable part of 

 the world, perhaps all the world there was, centred around their homes 

 and extended not many days' journey beyond their horizon. Early 

 voyagers must have experienced exceptional thrills from excursions into 

 regions that did not even exist ; doubtless their tales were given no more 

 credence than the reports of geologists who described terrestrial events 

 that preceded the creation of the world. 



It is surprising to realise that less than two thousand years ago our 

 predecessors had scarcely any reliable knowledge of world-geography, 

 and less of the configuration of the globe. An interesting study could be 

 made of the influence on philosophical ideas of the vast increase in the 

 conception of space that resulted from medizeval exploration. Our 

 modern ideas of cosmic space, whether curved or infinite, are in some 

 sense but a sequel to the revolutionary discovery that there was anything 

 of the sort to discover. 



Realisation of the immensity of geological time is relatively recent, 

 and it is far from universal even to-day. Whereas a conception of the 

 size, and even of the cosmic relations, of the world is subject to daily 

 experience and confirmation, that of past time is more subtle to obtain. 

 Modern transport and other inventions enable us to span in a day distances 

 greater than early conceptions of the size of the Universe ; but we are still 

 time-bound by the threescore years and ten of our earthly experience. 

 It may be doubted if anyone, even a geologist or a historian, can form a 

 clear idea of the significance of a thousand years of time ; while it is 

 probable that the four or five thousand years canonically ascribed to the 

 earth's existence seemed an almost infinite period to those who decided 

 upon it. And yet to-day we know that an interval of, say, 100,000 years 

 represents an infinitesimal part of world history, and does not cover even 

 the duration of mankind. We know, thanks to archaeological research, 

 of complex human civilisations antedating the official creation of the world ; 

 and we know, through geological research, of animals and plants that 

 populated the earth in eras a thousand times more remote. We know, 

 but we cannot truly comprehend. 



Although we must stand bewildered before the actual figures of geo- 

 logical time, more hopelessly than before those of cosmic space, there is 

 no serious difficulty in appraising relative time values. A million years 

 may be inconceivable, but they are obviously fewer than ten million or 

 a hundred million. We can mentally dispense with the cyphers, and 

 reduce the totals within the limits of our understanding. So that if we 

 estimate the duration of mankind at one million j'ears, and that of the 

 Cainozoic era (the ' age of Mammals ') up to the present at sixty million 

 years, the ratio of one to sixty is a true and intelligible expression of the 

 data. Whether we give credence to the estimates of the length of pre- 

 ceding eras or not, we can readily understand that they were collectively 

 vastly longer than the Cainozoic. And who shall say what vistas of time 

 are behind and beyond the mists of the pre-Cambrian .'' Without pre- 

 tending to ascribe to geologists an abnormal share of the attributes of 

 Deity, it is within the truth to say that they think in terms of time where 

 ' a thousand ages ' are lost in the total. 



