Classical. The first task of a speaker, the Greeks taught, is invention, in Greek heuresis: finding what to say. Aristotle devoted most of his Rhetoric to it. He gave speakers tools for finding arguments, for understanding emotions, and for presenting their own character.

Topics: the places of argument

Aristotle used the word topos, literally “place,” for a general pattern of argument, a place in the mind where a speaker could go to find arguments on any subject. In Book Two he listed many. Some of the most useful:

• From opposites: if self-control is good, lack of self-control is bad. If the opposite of a claim is true, the claim is false.
• From more and less: if even the gods do not know everything, humans surely do not. If someone beat his father, he would surely beat his neighbor.
• From definition: define the key term in a way that supports your case.
• From consequences: since an act has good or bad results, argue from whichever results suit your purpose.
• From previous judgments: appeal to what wise people, the gods, the city or the judges themselves have decided before.
• From inconsistency: point out that your opponent's past words or deeds contradict his present claims.

Aristotle also described common topics useful in every kind of speech: the possible and impossible, whether something did or did not happen, whether something will or will not happen, and greatness and smallness. A student who knew the topics could approach any question by running through them, as a builder runs through his tools.

Emotions

Aristotle's discussion of emotions, in Book Two, is one of the earliest systematic studies of psychology. For each emotion he asked three questions: what state of mind people are in when they feel it, toward whom they feel it, and on what grounds. Among the emotions he analyzed are anger and calmness, friendship and enmity, fear and confidence, shame, pity, indignation, envy and emulation.

His account of anger is a good example. Anger, he wrote, is a desire, accompanied by pain, for revenge for an apparent slight, by someone who has no right to slight us. People become angry when they are thwarted, when they are insulted, and especially when the slight comes from someone they think owes them respect. A speaker who wanted to rouse a jury's anger against his opponent would show that the opponent had slighted them or those they care about; one who wanted to calm it would show that the slight was unintended, or that the offender was humble and sorry.

On pity, Aristotle noted that we pity those whose suffering is undeserved and who are like us, so that we fear the same could happen to us. That is why defendants showed their children to the jury.

Character and audience

For ethos, Aristotle said the speaker must display three qualities: practical wisdom (phronēsis), virtue (aretē) and goodwill toward the audience (eunoia). Without wisdom, a speaker may be wrong; without virtue, he may lie; without goodwill, he may give poor advice even knowing better. A speaker who seems to have all three will be believed.

He also described the characters of different audiences. The young, he wrote, are passionate, hopeful, trusting, quick to anger and eager for honor. The old are cautious, suspicious, slow to hope and concerned with what is useful. Those in the prime of life fall between. The wealthy, the powerful and the fortunate each have typical traits. A speaker must adapt his arguments to his audience's character.

Worked example: running the topics

The question: should the city fund a public school for the children of poor citizens? A Greek student would run through the topics to find arguments. Here are some he might find on the side of yes.

• Opposites: if ignorance harms the city, education helps it.
• More and less: if we spend silver to train horses for the cavalry, should we spend nothing to train our children?
• Definition: a citizen is one who shares in judging and ruling; one who cannot read the laws shares in neither. Education makes citizens.
• Consequences: educated citizens serve better on juries, speak better in the Assembly and are less easily deceived by demagogues.
• Previous judgments: our ancestors trained every citizen in arms for the city's defense; training the mind defends the city too.

Now try the other side, using the same topics: consequences of the cost, more and less applied to other needs, and so on. Finally, choose an emotion to rouse in your audience, and decide how to show your own wisdom, virtue and goodwill. That combination of topics, emotions and character, worked out before a single sentence of the speech is written, is what the Greeks meant by invention.