Its teachings naturally called forth many protests, explanations, and supplements, and these have found the permanent place in the book that they rightfully deserve. Its fragmentary structure and abrupt transitions also made later insertions exceedingly easy. These are the simplest and the most natural explanation of the sharp contradictions that abound in the book (_cf. e.g_., ii. 22 and iii. 22, or iv. 2 and ix. 4, or iii. 16 and iii. 17, or viii. 14 and ix. 2, or iii. 1-9 and iii. 11). The preacher, whose painful experiences and prevailingly pessimistic teachings are the original basis of the book, appears to have been consistent throughout. He ends in xii. 8 with the same refrain, _Vanity of vanities; all is vanity!_ In a divine library like the Old Testament, reflecting every side of human thought and experience, such a book is not inappropriate. Its contradictions provoke thought; they beget also a true appreciation of the positive notes thus brought into dramatic contrast with the ground tones of pessimism which resound through all literature and history. XII THE HISTORY OF THE PSALTER [Sidenote: _Nature of the Psalter_] Corresponding to the book of Proverbs, itself a select library containing Israel's best gnomic literature, is the Psalter, the compendium of the nation's lyrical songs and hymns and prayers. It is the record of the soul experiences of the race. Its language is that of the heart, and its thoughts of common interest to worshipful humanity. It reflects almost every phase of religious feeling: penitence, doubt, remorse, confession, fear, faith, hope, adoration, and praise. Even the unlovely emotion of hatred is frankly expressed in certain of the imprecatory psalms. The Psalms appeal to mankind in every age and land because, being so divine and yet so human, they rest on the foundations of universal experience. Whenever a heart is breaking with sorrow or pulsating with thanksgiving and adoration, its strongest emotions find adequate expression in the simple and yet sublime language of the Psalter. [Sidenote: _Influence of the prophets upon it_]