Question: all flesh is grass meaning biology?
Answer: All flesh is grass is a much-quoted phrase from the Old Testament, Isaiah 40:6 (Hebrew: כָּל־הַבָּשָׂ֣ר חָצִ֔יר‎ kol habbasar chatsir). ... The phrase is interpreted to mean that human life is transitory ('impotent, perishing, limited').