[Footnote 15: Observe the brisk movement of these sentences. How they catch and hold the attention, giving a new impulse to the reader's interest!] [Footnote 16: Nature abhors a vacuum.] [Footnote 17: Noxious. Harmful.] [Footnote 18: John Locke (1632-1704), an English philosopher whose work was of especial significance in the development of modern philosophy. The work he is best known by is the exhaustive "Essay on the Human Understanding," in which he combated the theory of Descartes, that every man has certain "innate ideas." The innate-idea theory was first proved by the philosopher Descartes in this way. Descartes began his speculations from a standpoint of absolute doubt. Then he said, "I think, therefore I am," and from this formula he built up a number of ideas innate to the human mind, ideas which we cannot but hold. Locke's "Essay on the Human Understanding" did much to discredit Descartes' innate ideas, which had been very generally accepted in Europe before.] [Footnote 19: Francis Bacon, Baron Verulam, Viscount Saint Alban's (1561-1626), a famous English statesman and philosopher. He occupied high public offices, but in 1621 was convicted of taking bribes in his office of Lord Chancellor. He pleaded guilty and was sentenced to imprisonment and a fine of forty thousand pounds. Both these sentences were remitted, however. In the seventeenth century, judicial corruption was so common that Bacon's offence was not considered so gross as it would now be. As a philosopher Bacon's rank has been much disputed. While some claim that to his improved method of studying nature are chiefly to be attributed the prodigious strides taken by modern science, others deny him all merit in this respect. His best known works are: "The Novum Organum," a philosophical treatise; "The Advancement of Learning," a remarkable argument in favor of scholarship; and the short essays on subjects of common interest, usually printed under the simple title "Bacon's Essays."] [Footnote 20: Third Estate. The thirteenth century was the age when the national assemblies of most European countries were putting on their definite shape. In most of them the system of _estates_ prevailed. These in most countries were three--nobles, clergy, and commons, the commons being the third estate. During the French Revolution the Third Estate, or Tiers Etat, asserted its rights and became a powerful factor in French politics, choosing its own leaders and effecting the downfall of its oppressors.] [Footnote 21: Restorers of readings. Men who spend their lives trying to improve and correct the texts of classical authors, by comparing the old editions with each other and picking out the version which seem most in accordance with the authors' original work.] [Footnote 22: Emendators. The same as restorers of readings.] [Footnote 23: Bibliomaniacs. Men with a mania for collecting rare and beautiful books. Not a bad sort of mania, though Emerson never had any sympathy for it.]