http://en.wikipedia.org/wiki/Ecclesiastes
There is considerable disagreement among scholars as to just what Ecclesiastes is about: positive and life-affirming, or deeply pessimistic.[25] In the 5th century St Jerome established an allegorical reading that remained dominant for over a thousand years; then Luther and other Reformation theologians ushered in a literal and theological reading; and finally post-Enlightenment scholars applied the critical tools of the modern age.[26] The disagreements arise because passages of Ecclesiastes seem to contradict other portions of the Old Testament, and even itself. The question which continually arises is, is Koheleth coherent or incoherent, insightful or confused, orthodox or heterodox? Is the ultimate message of the book to copy Koheleth, the wise man, or to avoid his errors?[27]
One suggestion for resolving the contradictions is to read the book as the record of Koheleth's quest for knowledge: opposing judgements (e.g. the dead are better off than the living (4:2) vs. a living dog is better off than a dead lion (9:4)) are therefore provisional, and it is only at the conclusion that the verdict is delivered (11-12:7). On this reading, Koheleth's sayings are goads, designed to provoke dialogue and reflection in his readers, rather than to reach premature and self-assured conclusions.[28]
The subject of Ecclesiastes is the pain and frustration engendered by observing and meditating on the distortions and inequities pervading the world, the uselessness of human deeds, the limitations of wisdom and righteousness; all this coexists with a firm belief in God, whose power, justice and unpredictability are sovereign.[29] History and nature move in cycles, so that all events are predetermined and unchangeable, and life has no meaning or purpose: the wise man and the man who does not study wisdom will both die and be forgotten: man should be reverent ("Fear God"), but in this life it is best to simply enjoy God's gifts.[23]