38 
prove a universal law, the induction for which must necessarily be 
very extensive. With respect to the increase of food in an arith- 
metical ratio only, it has remained up to the present time little 
more than an assertion; no sufficient proofs have been advanced, 
and in fact everything points against its correctness, and the theory 
has of late years been softened down to this assertion simply,— 
that population tends to increase faster than subsistence. But 
although deprived of the original mathematical certainty, the con- 
sequences deduced from it remain unaltered. Seeing then that 
this theory has been the basis of other theories both in political 
economy and in development it may be interesting to us to enquire 
how far ancient and modern facts fall in with it as regards 
approaching over-population. What is known of the population 
of the world in former times as compared with it at present? Was 
it far below ? - Was it below it at all? No doubt much is wrapped 
in the uncertainty which obscures early times, but this ought to 
make us hesitate equally in hastily asserting geometrical progres- 
sion and in rashly denying it. Montesquieu, early in the 18th 
century, expressed what seems to have been then the received im- 
pression, that the population of the world had long been declining. 
Since his time everybody has taken up the opposite opinion. Yet 
consider for a moment the empires of antiquity, and the enormous 
populations which must have been necessary to carry out those 
works of irrigation and architecture, the ruins of which literally 
cover the face of the earth. We are looking at the world as a 
whole, not at any limited portion of-it. No one will deny that any 
particular district may be thinly populated at one time and over- 
crowded at another. Europe is generally pointed-out at present 
as accomplishing the geometrical progression. But after all these 
centuries of increasing civilisation she does not yet number 86 to 
square mile. And Asia is not 46. Compare this with Great 
Britain which numbers 324 to the square mile. The whole world 
averages 29. The numbers in Asia were once probably very much 
higher proportionally than in Europe. We have only to glance 
back over the pages of history to satisfy ourselves that the great 
centres of population have changed their places repeatedly and 
rapidly, but they have always been in existence. There is no 
period of history without its great empires and crowded populations ; 
and all the signs of pre-historic periods point in the same direction 
in each hemisphere. Large areas now barren and desolate were 
once thickly peopled and highly cultivated. Nowhere is this more 
evident than in west and south-west Asia. The valley of the Syr 
Daria is saidto have been at one time so thickly settled that a 
nightingale could fly among the fruit trees along its whole distance 
to the Sea of Aral. The whole country from this river to the Nile 
