One time he was asked if he believed in an afterlife. After a moment's hesitation he said no, that he thought there was only "some kind of velvety cool blackness," adding then: "Of course, I admit I may be wrong. It is conceivable that I might well be reborn as a Chinese coolie. In such case I should lodge a protest."
To know, is to know that you know nothing. That is the meaning of true knowledge. When you say something, say what you know. When you don't know something, say you don't know. That is knowledge.