Wisdom from the Early Stoics, Zeno of Citium 38

Posidonius defines dialectic as the science dealing with truth, falsehood, and that which is neither true nor false; whereas Chrysippus takes its subject to be signs and things signified. Such then is the gist of what the Stoics say in their theory of language.

To the department dealing with things as such and things signified is assigned the doctrine of expressions, including those which are complete in themselves, as well as judgements and syllogisms and that of defective expressions comprising predicates both direct and reversed. 

By verbal expression they mean that of which the content corresponds to some rational presentation. 

Of such expressions the Stoics say that some are complete in themselves and others defective. 

Those are defective the enunciation of which is unfinished, as e.g. "writes," for we inquire "Who?" Whereas in those that are complete in themselves the enunciation is finished, as "Socrates writes." 

And so under the head of defective expressions are ranged all predicates, while under those complete in themselves fall judgements, syllogisms, questions, and inquiries.

—Diogenes Laërtius, 7.62-63