Charles Ellicott Commentary Ecclesiastes 3:21

"Who knoweth the spirit of man, whether it goeth upward, and the spirit of the beast, whether it goeth downward to the earth?" — Ecclesiastes 3:21 (ASV)

The Septuagint, followed by a great body of interpreters, ancient and modern, translate, Who knoweth whether the spirit of man goeth upward? etc., and this agrees better with the context of this paragraph. The skeptical thought is, “We see that death resolves into dust (Genesis 3:19; Ecclesiastes 12:7) the bodies of men and animals alike; and if it is alleged that there is a difference as to what becomes of their spirits, can this be asserted with the certainty of knowledge?” The writer here seems to have read both Psalms 49:14 and Proverbs 15:24.