Stranger: 'Are not thought and speech the same, with this exception, that what is called thought is the unuttered conversation of the soul with herself?
Theatetus: Quite true.
Stranger: But the stream of thought which flows through the lips and is audible is called speech?
Theatetus: True.
Stranger: And we know that there exists in speech...
Theatetus: What exists?
Stranger: Affirmation
Theatetus: Yes, we know it.
Autor: Plato