What is the "etymology" of the symbol ∀ (for all), the universal quantifier. I can't find anything here, but I suspect it was adopted in the same way our numerals were adopted.
REMARK ABOUT A COMMENT
As simchona has pointed out, the symbol appears to have come from a shorthand (see here) from Gerhard Gentzen's publication "Investigations into Logical Deduction" in the The American Philosophical Quarterly, a symbol which shares an interesting likeness to the symbol in the link above. Perhaps the symbol had an earlier meaning, which gave reason to its usage in the Gentzenian way. Thank you, simchona.