Heinrich von Treitschke, Politik, Vol. I, pp. 223-224. Leipzig, 1897.

Plato, Critias, 112. Aristotle, Politics, Book II, chap. VII; Book IV, chap. IV; Book VII, chap. IV.

Plato, De Legibus, Book V, chaps. 8, 9, 10, 11.

Roscher, National-Oekonomik des Handels und Gewerbefleisses, pp. 180-187. Stuttgart, 1899.

Blanqui, History of Political Economy, pp. 150-152. New York, 1880.

Carl Ritter, Comparative Geography, p. 63. New York, 1865.

E. C. Semple, American History and its Geographic Conditions, pp. 42-43, 109, 110. Boston, 1903.

James Bryce, Impressions of South Africa, pp. 405-6. New York, 1897.

P. L. Ford, Writings of Thomas Jefferson, Vol. VIII. Letter to John Bacon, April 30, 1803; and Confidential Message to Congress on the Expedition to the Pacific, January 18, 1803.

Emerson, The Young American, in Nature Addresses and Lectures, pp. 369-371. Centenary Edition, Boston.