Much about this OT book is mysterious—who wrote it and when and what its message is. Not once is it quoted in the NT; and in the 1st cent. CE the rabbinic school of Shammai questioned whether it should be regarded as part of holy scripture, though the more liberal Hillel did accept it. (One practical effect of this was that the liberal school felt obliged to wash after touching it, since touching a book that belongs to the canon renders the hands unclean.)
In Hebrew the title of the book is Qoheleth (and the Greek title, in the translation of Aquila—there is no version in the LXX—may be an attempted interpretation of this) which has come to be translated ‘the Preacher’; the late form of the book's Hebrew indicates that King Solomon could not have been the author (cf. Eccles. 1: 12), and its links with Hebrew wisdom literature suggest a date for it of about 200 BCE. Is the pursuit of pleasure or riches or work or womanizing the way of wisdom (Eccles. 2: 3 ff.)? Not so: all end in death. Time and again the author dismisses what passes for human existence as fleeting, futile, and ‘vanity’; and there are strict limits to understanding any guiding purposes. Life’s ambiguities had best be accepted and that which is satisfying should be enjoyed while it lasts (Eccles. 8: 14–15) for good things will surely come to an end (Eccles. 12: 1–2). Rather than expressing a hope of life after death, the readers must put their trust in God (12: 14: cf. Ps. 88: 9–13), though it is not true that God inevitably rewards the just in this present life. It is all a matter of time and chance (Eccles. 9: 11–12): but it is advisable to keep on good terms with God, and not hurt oneself by useless resentment of what inevitably happens (Eccles. 3: 1–8).
Modern scholarship has felt that the combination of scepticism and conventional moral advice is evidence that the book as we have it was the work of more than one author. Possibly a basically sceptical book was worked over by an editor to make it acceptable to more orthodox readers. An alternative hypothesis of the composition of Ecclesiastes was put forward by Form Critics: a miscellaneous collection of independent proverbs which had been in circulation orally was collected into an anthology without regard to their theological compatibility. These two views about the book are to some extent brought together by Redaction Critics who suggest that advice to enjoy life while the opportunity lasts (as in 11: 9 ff.) has been put by a redactor into a religious context: we are to enjoy what God gives and to remember that he is the judge at the hour of death (12: 1a). On the other hand, it has been argued in favour of the unity of the work that inconsistency is a characteristic mark of some ancient writings. The book could itself be pointing to the self-contradictions of wisdom. At any rate the final advice to fear God (12: 13) stands. And some Christians maintaining a stern doctrine of original sin have not been unsympathetic to the Preacher’s portrayal of the unmitigated wickedness and injustice of the world.