We see then that each of those principles which rule in physical modification is equally true of mental modification. But though the modes of mental variation may be fairly clear, we must not be carried away by the view that therefore great changes in man are to be expected. The effects of various conditions upon the body are tolerably familiar, yet the average form of man has varied extraordinarily little during ten thousand years. The highest type of ancient man differs almost inappreciably from the highest type of modern man, certainly by not a tenth of the difference that may be seen between different types at present. It may be practically said that man is at a standstill in physical development. Sanitary improvements and better feeding may do great things, but they leave the essential form and constitution unaltered. The same is true of mind. When we become familiar with details of early ages nothing is more astonishing than to see how unaltered the mind of man is in its essentials. In tales and maxims six thousand years old we see not only the common stock of primary instincts, but also the _finesse_ of conduct in public life, the modes of ensuring respect in dealing with superiors and inferiors, the attention to very varied elements of character, and a fine suavity and kindliness pervading the whole. There is not a single class or a single public body at present that practically stands as high as the ideal of two hundred generations ago. And when we look at the material civilisation we see still farther back the appreciation of qualities of work which only a very small proportion of mankind care for now. The overwhelming zeal for minute accuracy was as perfect a mental state at 4700 B.C. as it is in a Royal Society paper of our day. The subject and the method have changed; but the mental attitude is the same in a man who demanded, and in those who executed, beautifully true plane surfaces, and long measurements exact to far within the variation of size caused by a hot or a cold day, and the men now who triangulate a continent and measure the world. The mind is the same, only the stock-in-trade of it has increased. At the beginning of history the palaces were adorned with table services cut in the hardest and most beautiful stones, exquisitely formed and polished; and such homes were assuredly inhabited by men whose tastes and artistic sense were closely the same as the best of ours, and who would, like us, have revolted at most of the products of the present time. Not only was there the body of highly skilled and intelligent men to do such work, but there must have been a widely spread standard of taste demanding this exquisite work as an aesthetic pleasure. The nature of mind is unchanged, its motives, its feelings, its sense of life; only in knowledge and the applications of it do we differ from the earliest civilisation that we can trace.