As an inevitable result of this decrease of water, and other natural conditions, vast areas of land on both sides of our tropical zones have become deserts; and it is a scientific certainty that this process of desertism will, and must continue, until it covers the whole world. But, I think, the end will long be delayed, for the loss by desertism will, as it seems to me, for ages be compensated by the new and habitable land arising from areas now covered by water. The old sea-beds upon Mars are now the most fertile areas upon that planet. As the desertism increases conditions similar to those of Mars will arise; the earth will become more level, polar glaciation will cease, the atmosphere become thinner, and water vapour, instead of falling as rain, will be carried by circulatory currents to the poles, and there be deposited as snow. What the Martians have accomplished has shown us how to stave off the water difficulty, and also how a highly civilised and intelligent people can bravely and calmly face the end which they clearly foresee! This is the lesson from the present physical condition of Mars. On the other hand, the continual progress of civilisation upon Mars, and the very high development attained there, coupled with what we know of our own progress during the ages past, give certainty to the hope that our own civilisation will continue to develop, slowly indeed, but surely; and also to the belief that, compared to what it will be in the future, our present stage of civilisation is merely savagery. Development will lead to progress in everything which tends to increase the intelligence, wisdom, and happiness of the whole human race. Our world has seen the rise and fall of many civilisations, but fresh ones have risen, phoenix-like, from the ashes of those which have departed and been forgotten. "The individual withers," but "the world is more and more." As it was in the past, so will it be in the future--ever-changing, ever-passing, but ever-renewing, until the final stage is reached. Since the earliest dawn of our creation the watchword of humanity has been "Onward!" and it is still "Onward!" but also "Upward!!" The possibilities of the development of the human race in the ages yet to come are so vast as to be beyond our conception; for, as Sir Oliver Lodge has remarked, "Eye hath not seen, nor ear heard, nor has it entered into the mind of man to conceive what the future has in store for humanity!" Then: "Forward, forward, let us range, Let the great world spin for ever down the ringing grooves of change!"