Despite the lack of structure, there are certain themes running through the Book that reappear at various points. The New Oxford Annotated Apocrypha identifies ten major recurring topics:

1. The Creation (16:24–17:24, 18:1–14; 33:7–15; 39:12–35; and 42:15–43:33);
2. Death (11:26–28; 22:11–12; 38:16–23; and 41:1–13);
3. Friendship (6:5–17; 9:10–16: 19:13–17; 22:19–26: 27:16–21; and 36:23–37:15);
4. Happiness (25:1–11; 30:14–25; and 40:1–30);
5. Honor and shame (4:20–6:4; 10:19–11:6; and 41:14–42:8);
6. Money matters (3:30–4:10; 11:7–28; 13:1–14:19; 29:1–28; and 31:1–11);
7. Sin (7:1–17; 15:11–20; 16:1–17:32; 18:30–19:3; 21:1–10; 22:27–23:27; and 26:28–28:7);
8. Social justice (4:1–10; 34:21–27; and 35:14–26);
9. Speech (5:6,9-15; 18:15–29; 19:4–17; 20:1–31; 23:7–15; 27:4–7; 27:11–15; and 28:8–26); and
10. Women (9:1–9; 23:22–27; 25:13–26:27; 36:26–31; and 42:9–14).

The Wisdom of Sirach is a collection of ethical teachings. Thus Ecclesiasticus closely resembles Proverbs, except that, unlike the latter, it is presented as the work of a single author, not an anthology of maxims drawn from various sources, presented in verse form. The question of which apothegms actually originated with Sirach is open to debate, although scholars tend to regard him as a compiler or anthologist.

The teachings are applicable to all conditions of life: to parents and children, to husbands and wives, to the young, to masters, to friends, to the rich, and to the poor. Many of them are rules of courtesy and politeness; and a still greater number contain advice and instruction as to the duties of man toward himself and others, especially the poor, as well as toward society and the state, and most of all toward God.

Wisdom, in ben Sirach’s view, is synonymous with the fear of God, and sometimes is identified in his mind with adherence to the Mosaic law. The maxims are expressed in exact formulas, and are illustrated by striking images. They show a profound knowledge of the human heart, the disillusionment of experience, a fraternal sympathy with the poor and the oppressed.

By contrast, Sirach exhibits little compassion for either women or slaves, and advocates distrust and possessiveness over women, and the harsh treatment of slaves (which presupposes the validity of slavery as an institution), positions which are not only difficult for modern readers, but cannot be completely reconciled with the social milieu at the time of its composition.

As in Ecclesiastes, two opposing tendencies war in the author: the faith and the morality of olden times, which are stronger than all argument, and an Epicureanism of modern date. Occasionally Sirach digresses to attack theories which he considers dangerous; for example, that man has no freedom of will, and that God is indifferent to the actions of mankind and does not reward virtue. Some of the refutations of these views are developed at considerable length.

Through these moralistic chapters runs the prayer of Israel imploring God to gather together his scattered children, to bring to fulfilment the predictions of the Prophets, and to have mercy upon his Temple and his people. The book concludes with a justification of God, whose wisdom and greatness are said to be revealed in all God’s works as well as in the history of Israel. These chapters are completed by the author’s signature, and are followed by two hymns, the latter apparently a sort of alphabetical acrostic.