We have here the limits of such an inquiry as the present. Placing the end of the age of electricity at provisionally about a hundred years hence (but it is quite conceivable that the rate of progress may overtake it earlier and shut the door on conjecture) it is possible to forecast, not indeed with certainty, but with a measure of imaginative probability, what will happen as the resources of electricity are developed and the other material amenities of the world are worked along the line of natural progress. So far as the light of analogy can point the way the reader is invited on a sort of conjectural journey. Of the developments of the moral ideas of man likely to be determined, not so much by the coming change in his material environment, as by the evolution of inner forces already at work, I propose to say something at the end of the book. In the meantime, the probable material changes in the next hundred years (or less, according to the rate of our progress) in various departments of life will be the subject of some intermediate conjectures. CHAPTER II HOUSING, TRAVEL AND POPULATION QUESTIONS When every allowance has been made for the material changes which the progress of this century threatens, it is easy to see that certain present-day problems will continue to trouble our successors. Some things which perplex ourselves will, I think, work out their own remedy. Others will remain the subject of solutions not difficult to be imagined in advance. One chief difficulty which will infallibly confront the immediate future, and even the future that is more remote, arises out of the simple fact that the race of man tends to increase numerically at a speed greater than our devices for its accommodation can quite conveniently cope with. The population of the world not only increases, but increases at compound interest. Nor is this all. Improved sanitation, better habits of life, and the progress of medicine, prolong lives that in the conditions of last century would have been shortened, and the rate of increase is thus further accelerated, as individuals who in different conditions would have died, live on, perhaps reproducing their species, and thus intensifying the population problem. Against these influences may be set the effect of the restrictions imposed by some civilised peoples on the birth rate, which Mr Roosevelt calls "race suicide." These practices, just now increasingly prevalent, retard the rate of increase, but do not at present stop our increase: they alleviate, but do not cure the difficulty of over-population. Artificial physiological checks on population, if I am right in certain other conjectures to be presently developed, will not form part of the permanent morality of the new age, partly because, with more enlightenment, they will be voluntarily abandoned or superseded, and partly because the necessity for them will have disappeared, having worked out its own cure.