Too much openness and you accept every notion, idea, and hypothesis-which is tantamount to knowing nothing. Too much skepticism-especially rejection of new ideas before they are adequately tested-and you're not only unpleasantly grumpy, but also closed to the advance of science. A judicious mix is what we need.
Conversation with a friend will only bear good fruit of knowledge when both think only of the matter under consideration and forget that they are friends.
They assembled together and dedicated these as the first-fruits of their love to Apollo in his Delphic temple, inscribing there those maxims which are on every tongue- 'know thyselP and 'Nothing overmuch.'
To know how little one knows is to have genuine knowledge. Not to know how little one knows is to be deluded. Only those who know when they are deluded can free themselves from such delusion. The intelligent people are not deluded, because they know and accept their ignorance as ignorance, and thereby have genuine knowledge.