Whatever may be thought of these propositions as matters of theory, the doctrine of a general and steady law of progress is one to which no historian ought to commit himself. His business is to set forth and explain the facts exactly as they are; and if he writes in the light of a theory he is pretty certain to be unconsciously seduced into giving undue prominence to those facts which make for it. Moreover, the question is in itself a far more complex one than the simple word “progress” at first sight conveys. What is the test of progress? In what form of human advance is it to be deemed to consist? Which of these forms is of the highest value? There can be no doubt of the advance made by man in certain directions. There may be great doubt as to his advance in other directions. There may possibly be no advance but even retrogression, or at least signs of an approaching retrogression, in some few directions. The view to be taken of the relative importance of these lines of movement is a matter not so much for the historian as for the philosopher, and its discussion would carry us away into fields of thought not fitted for a book like the present. Although, therefore, it is true that one chief interest of history resides in its capacity for throwing light on this question, all that need here be said may be expressed as follows: There has been a marvellous advance in man’s knowledge of the laws of Nature and of his consequent mastery over Nature. There has been therewith a great increase in population, and, on the whole, in the physical vigour of the average individual man. There has been, as a further consequence, an immense increase in the material comfort and well-being of the bulk of mankind, so that to most men necessaries have become easier of attainment, and many things which were once luxuries have become necessaries. Against this is to be set the fact that some of the natural resources of the world are being rapidly exhausted. This would at one time have excited alarm; but scientific discoveries have so greatly extended man’s capacity to utilise other sources of natural energy, that people are disposed to assume that the loss of the resources aforesaid will be compensated by further discoveries. [Sidenote: The Gain and the Loss]