For this purpose, the propositions of common speech may be viewed as consisting of two Terms, a linkword called the copula (positive or negative) expressing a relation between them, and certain symbols of quantity used to express that relation more precisely.
Let us indicate the Subject term by S, and the Predicate term by P.
All propositions may be analysed into one or other of four forms:—
All S is P,
No S is P,
Some S is P,
Some S is not P.
All S is P is called the Universal Affirmative, and is indicated by the symbol A (the first vowel of Affirmo).
No S is P is called the Universal Negative, symbol E (the first vowel of Nego).