Brewer's Dictionary of Phrase and Fable/A (letter)
A. This letter is modified from the Hebrew א (aleph = an ox), which was meant to indicate the outline of an ox's head.
A among the Egyptians is denoted by the hieroglyphic which represents the ibis. Among the Greeks it was the symbol of a bad augury in the sacrifices.
A in logic is the symbol of a universal affirmative. A asserts, E denies. Thus, syllogisms in barbara contain three universal affirmative propositions.