In one ep (Who Mourns for Adonis) Kirk realizes that the ancient Greek gods were actually space travellers. In a slightly later ep (Of bread and circuses) he finds a planet where ancient Roman gods are worshipped and fails to recall his acquired knowledge of the similar Greek gods being space travellers. In still a later ep (Plato's Stepchidren) Kirk meets up with a bunch of Platonians who visited EARth during the ancient Grerek days and he never asks the Platonians if they knew the ancient travellers who were believed to be Greek gods or anything.