heaven. "Know thyself" and "Nothing too much" were
inscribed upon the Delphic oracle.

"Know then thyself, presume not God to scan;
The proper study of mankind is man."

]

[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 comm