It’s not just that it sounds older and authoritative and was used in the bible. It’s worth noting one of the most famous biblical phrases in which it appears. Psalm 91 says that our lifespan is “three score years and ten” (I.e., 70), but that some may even live to “four score years”. <br><br>Lincoln draws an analogy between the nation and a person (“our <b>fathers</b> brought forth a new nation, <b>conceived</b> in Liberty...”) to ask if the nation — and perhaps democracies in general — have a similar lifespan, doomed to eventually tear themselves apart. “Four score and seven” would imply that the nation, like a very elderly person, is already on borrowed time.