10. Much more care and time must be devoted than has been done hitherto to corporal exercise, to gymnastics and swimming; but it is especially important to have walks in common every week, and journeys on foot during the holidays. The lesson in observation which they obtain in this way is invaluable. The chief aim of higher education up to the present time, in most countries, has been a preparation for the subsequent profession, and the acquisition of a certain amount of information and direction for civic duties. The school of the twentieth century will have for its main object the formation of independent thought, the clear understanding of the knowledge acquired, and an insight into the natural connection of phenomena. If the modern state gives every citizen a vote, it should also give him the means of developing his reason by a proper education, in order to make a rational use of his vote for the commonweal. CHAPTER XX SOLUTION OF THE WORLD-PROBLEMS A Glance at the Progress of the Nineteenth Century in Solving Cosmic Problems--I. Progress of Astronomy and Cosmology--Physical and Chemical Unity of the Universe--Cosmic Metamorphoses--Evolution of the Planetary System--Analogy of the Phylogenetic Processes on the Earth and on Other Planets--Organic Inhabitants of Other Heavenly Bodies--Periodic Variation in the Making of Worlds--II. Progress of Geology and Palæontology--Neptunism and Vulcanism--Theory of Continuity--III. Progress of Physics and Chemistry--IV. Progress of Biology--Cellular Theory and Theory of Descent--V. Anthropology--Origin of Man--General Conclusion