David Bentley Hart on Greek and Hebrew Concepts of "Eternity"

Take, for example, the Greek phrase εις τον αιωνα (eis ton aiōna), which is typically rendered into English as “forever,” as is correct if one is pedantically precise about the etymological presence of the Latin word aevum in the English word “forever,” but which might better be rendered today as something like “unto the age” or “for the age.” This is the equivalent of the Hebrew le-olam or ad-olam, which principal connotation would be something like “from now till the end of this age.” Or take the phrases εις τους αιωνας των αιωνων (eis tous aiōnas tōn aiōnōn)—“the age of the ages”—and ο αιων των αιωνων (^ho aiōn tōn aiōnōn)—“the age of the ages.” These are standard Greek correlates of such Hebrew phrases as le-olam va-ed (“unto an age and beyond”) or le olamei-olamim (“unto ages of ages”), which perhaps indicate something like eternity, but which also might be taken as meaning simply an indeterminately vast period of time. (David Bentley Hart, That All Shall be Saved: Heaven, Hell, and Universal Salvation [New Haven: Yale University Press, 2019], 126)