Wisdom from the Early Stoics, Zeno of Citium 48

Symbolical argument is a combination of full argument and mood; e.g. "If Plato is alive, he breathes; but the first is true, therefore the second is true." 

This mode of argument was introduced in order that when dealing with long complex arguments we should not have to repeat the minor premise, if it be long, and then state the conclusion, but may arrive at the conclusion as concisely as possible: if A, then B. 

Of arguments some are conclusive, others inconclusive. 

Inconclusive are such that the contradictory of the conclusion is not incompatible with combination of the premises, as in the following: "If it is day, it is light; but it is day, therefore Dion walks." 

Of conclusive some are denoted by the common name of the whole class, "conclusive proper," others are called syllogistic. 

The syllogistic are such as either do not admit of, or are reducible to such as do not admit of, immediate proof in respect of one or more of the premises; e.g. "If Dion walks, then Dion is in motion; but Dion is walking, therefore Dion is in motion." 

Conclusive specifically are those which draw conclusions, but not by syllogism; e.g. the statement "It is both day and night" is false: "now it is day; therefore it is not night." 

Arguments not syllogistic are those which plausibly resemble syllogistic arguments, but are not cogent proof; e.g. "If Dion is a horse, he is an animal; but Dion is not a horse, therefore he is not an animal." 

—Diogenes Laërtius, 7.77-78