The central message of Ecclesiastes may be encapsulated in a single word: Hevel, usually translated as “vanity.” The word appears 38 times in the text, and it is clearly critical to understanding the book’s message. It is most commonly understood to mean futility or meaninglessness, or the idea that anything we do is in vain. Yet Hevel is also the Hebrew name of Abel, Cain’s brother, the son of Adam and Eve. Therefore, we must first remind ourselves of the original text in Genesis to which Kohelet is referring.
Ethan Dor-Shav, “Ecclesiastes, Fleeting and Timeless”, Azure No. 18 (Autumn 2004), 72.