Wisdom from the Early Stoics, Zeno of Citium 42

The followers of Chrysippus, Archedemus, Athenodorus, Antipater and Crinis divide propositions into simple and not simple. 

Simple are those that consist of one or more propositions which are not ambiguous, as "It is day." 

Not simple are those that consist of one or more ambiguous propositions. They may, that is, consist either of a single ambiguous proposition, e.g. "If it is day, it is day," or of more than one proposition, e.g. "If it is day, it is light."

With simple propositions are classed those of negation, denial, privation, affirmation, the definitive and the indefinitive; with those that are not simple the hypothetical, the inferential, the coupled or complex, the disjunctive, the causal, and that which indicates more or less. 

An example of a negative proposition is "It is not day." Of the negative proposition one species is the double negative. By double negative is meant the negation of a negation, e.g. "It is not not-day." Now this presupposes that it is day. 

A denial contains a negative part or particle and a predication: such as this, "No one is walking." 

A privative proposition is one that contains a privative particle reversing the effect of a judgement, as, for example, "This man is unkind." 

An affirmative or assertory proposition is one that consists of a noun in the nominative case and a predicate, as "Dion is walking." 

A definitive proposition is one that consists of a demonstrative in the nominative case and a predicate, as "This man is walking." 

An indefinitive proposition is one that consists of an indefinite word or words and a predicate, e.g. "Some one is walking," or "There's some one walking"; "He is in motion." 

—Diogenes Laërtius, 7.68-70