“vanity” of life

From ESV Study Bible.

The “vanity” of life. The book begins and ends with the exclamation, “Vanity of vanities! All is vanity” (Eccles. 1:2; 12:8). While “vanity” is obviously a key word throughout the book (its 38 occurrences account for more than half of its total usage in the OT), it is notoriously difficult to translate. Literally the word means “vapor” (see esv footnote on 1:2) and conjures up a picture of something fleeting, ephemeral, and elusive, with different nuances to be ascertained from each context. When applied to human undertakings or the pleasures and joys of earthly life, it indicates that “the present form of this world is passing away” (1 Cor. 7:31); applied to the darker realities of living in a fallen world (e.g., death), it expresses frustration, anger, or sorrow; applied to the Preacher's search for understanding of all things, it indicates something that remained incomprehensible or inscrutable to him (e.g., Eccles. 1:14–15). This last-mentioned usage is particularly significant, as the book presents itself as primarily a quest to “figure out” all of life (see esp. 1:12–18).