Q. How do we know how tall Giants are?
A. Giants must be at least 15 cubits tall (23 feet tall).
Why? Yea, it is a matter of logic. The Bible tells us that the Great Flood covered the mountains by 15 cubits, killing all flesh. Yet, the antedeluvian Giants, the Nephilim of Genesis 6, appear alive and well after the flood (in Numbers 13). Ergo, the Giants who survived the flood must have been more than 15 cubits tall!
(This otherwise unimpeachable logic ignores any other ingenious ways that Giants managed to survive the Flood. Some rabbinic sources claim that Og managed to escape the Flood by holding onto the outside of Noah’s Ark).
Walter Stephens, in his wonderful book, Giants in Those Days, describes this lost medieval knowledge, concerning the height of Giants, as “an erudite commonplace”. Stephens mentions the Twelfth-century theologian Honorius of Autun or Honorius Augustodunensis (PL 172.165) and Sixteenth-century Italian man of letters, Francesco Sansovino as two scholars who had amassed much erudition concerning the height of Giants (65).
Sansovino quotes Tuscan folk as saying: “Ed hebbi voglia anco io d’esser gigante / Vedi che sette braccia sono a punto.” According to Stephens, these lines didn’t really originate with Tuscan folk at all. Instead, they reproduce part of the half-Giant Margutte’s self-description in the Fifteenth-century work by Luigi Pulci, Morgante: “Ed ebbi voglia anco io d’esser gigante, / Poi mi penti’ quando al mezzo fu’ giunto, / Vedi che sette braccia sono a punto” (18.113.6-8).
Why was Margutte a ‘half-giant’? Because he was only 7 cubits, not 15 cubits, tall. As Stephens translates the lines quoted from Morgante, above: “And I also desired to be a Giant, but I thought better of it when I had arrived halfway–note that I’m exactly seven cubits tall.”