The Book of Proverbs bears the title "The Proverbs of Solomon son of David, King of Israel." Other titles scattered through the book prove that it is made up of several collections of proverbs which once circulated independently. Thus Prov. 10 begins, "The Proverbs of Solomon"; xxii. 17-21 is an introduction inviting the reader to give attention to "Sayings of Sages," and dwelling on the profit of so doing; xxiv. 23, "These also are by the Sages"; xxv. 1, "These also are Proverbs of Solomon which the men of Hezekiah king of Judah edited"; xxx. 1, "The Sayings of Agur son of Jakeh"; xxxi. 1, "The sayings of Lemuel King of Massa (?), which his mother taught him"; finally, xxxi. 10-31 is an anonymous alphabetic poem in praise of the good housewife. The inference of diverse origin drawn from these titles is confirmed by diversity of character and form, and by the repetition of proverbs in the different sections, especially in Prov. x. 1-xxii. 16 and cc. 25-29; on the other hand, the similarity of all parts of the book in thought and expression indicates that there is among them no wide difference in time. The theme of the book is "wisdom," by which is meant primarily a practical wisdom in the conduct of individual life under the social, political, and economic conditions of the time. The end is a prosperous and happy life, and the motive is enlightened self-interest. Experience shows that morality conduces to prosperity and happiness, and immoral and unsocial actions to the opposite. To inculcate this truth and to apply it is the aim of the wise, who make this knowledge the foundation of virtue and of well-being. Their instruction is not given in the form of a philosophical ethic, with a discussion of the nature of the highest good and of the principles and motives of conduct, but in sententious maxims, or aphorisms, sometimes grouped upon a central theme, often without any thread of connection. Religion is affirmed by the most reflective of these authors to be the first principle of wisdom (Prov. i. 7; ix. 10; cf. xv. 33), but there is no appeal to a divine law or to the conscience of the individual; the maxims are based on observation and experience. The opposite of wisdom is folly; it is an unintelligent selfishness which ignores the consequences of its course, and sooner or later involves itself in loss or ruin. For ruin is the end of persistent folly as happiness is the fruit of wisdom. This is the order of the world; God's ordering, no doubt, but working itself out by natural law. Wise men and fools are two permanent classes of men, divided by as hard a line as in the Stoic ethics is drawn between the virtuous man and the rest of mankind. The authors know no degrees of wisdom; they recognize different kinds of folly, but no difference in fools.