In the writings of Alcmaeon of Croton (5^th century BC) one can find an description of the two ways of knowledge, that of aletheia and doxa:

“About invisible things, about divine things only gods have a precise knowledge. But inasmuch as one can infer from the evidence of things of humans (viz. perceived by the senses), most of them go in pairs. Thus by sight we distinguish white from black and the large from the small, by ears a good word from a bad word, by smell a pleasant odor from a disgusting one, by taste sweet from bitter, and by touch smooth from rough.”

The above quotation is from prof. Andrei Lebedev's article: Alcmaeon of Croton on Human Knowledge, the Seasons of Life, and Isonomia: A New Reading of B 1 DK and Two Additional Fragments from Turba Philosophorum and Aristotle.

According to Lebedev, Alcmaeon inferred that the duality of all sensiblia reflects the dualistic nature of all sensible things, i.e. that all bodies are composed of opposite elements or 'dynameis'. This way of understanding the difference between human and divine knowledge was typical for archaic Greek philosophy. Lebedev adds that apart from Alcmaeon, it is found in Xenophanes, Parmenides, and Heraclitus: ”The duality of all sensible phenomena was commonplace in archaic Greek metaphysics and physics. In Heraclitus, exactly as in Parmenides, superior divine knowledge is “knowing all things as one”, and inferior human knowledge is concerned with opposites.”