The history of logic deals with the study of the development of the science of valid inference . Formal logics developed in ancient times in India, China ...
(There are many textbooks in this area; this list is by necessity incomplete.)
This logos holds always but humans always prove unable to understand it, both before hearing it and when they have first heard it. For though all things come to be in accordance with this logos , humans are like the inexperienced when they experience such words and deeds as I set out, distinguishing each in accordance with its nature and saying how it is. But other people fail to notice what they do when awake, just as they forget what they do while asleep.
But he recognizes that this is subject to a criticism: