Unfortunately the text-books which we now possess do not discuss, with any approach to exhaustiveness, the districts where their readers live; and hence they cannot give any true inductive generalization of the large and the remote. In ancient times, the study of geography began with the world of nature, not with the world of books. Herodotus, being 444 years B. C., became, by virtue of his investigations on his wanderings, the first critical geographer of the Greeks. Polybius traveled through the Alps and Pyrenees, Gaul and Spain, to be able to write the history of Hannibal’s campaigns. He explored the Black Sea and Egypt, in quest of facts. He is the father of all military geography; the greatest strategists have busied themselves with writing commentaries on Polybius. Strabo, the most industrious geographer of his age, did not write till he had traveled from the Caucasus to the Rhone, and from the Alps to Ethiopia. Philip Cluver, of Dantzig, who died in 1623, the true founder of classical geography, collected, by personal investigations, the materials of his great work on Germany, Italy, and ancient Sicily, all of which countries he traversed thoroughly, the classic authors in his hand. Alexander von Humboldt has become, by his thorough studies of nature in Europe, Asia, and America, the founder of Comparative Geography. He was thoroughly acquainted with every geographical form in the neighborhood of his home, before he traveled into foreign lands. These examples show that personal investigation is one of the most reliable of all sources of geographical knowledge. The second class of these sources is the accounts given in the published memoirs of travelers. In more primitive days than these, when very little was known regarding the earth, personal examination was easily completed, with a good degree of fullness, by almost any tourist. With the advance of knowledge, the narratives of travelers have increased, and the sum total of facts observed has become unwieldy; and, where facts have been wanting, the imagination has amply supplied their place. Of course, a single life soon became too short for the personal examination of every quarter of the globe; the narratives of those who had thoroughly explored any one were accepted as authoritative, and these accounts soon became the most generally available of all the sources of geographical knowledge. Yet, with this limitation, that now their abundance and their exactness tend to repress and almost to destroy any personal inquiry whatever. Nothing can take the place of some exploration and investigation on the part of the student of geography.