H.l. Mencken said this quote
“ Indeed it may be said with some confidence that the average man never really thinks from end to end of his life. There are moments when his cogitations are relatively more respectable than usual, but even at their climaxes they never reach anything properly describable as the level of serious thought. The mental activity of such people is only a mouthing of clichés. What they mistake for thought is simply a repetition of what they have heard. My guess is that well over eighty per cent. of the human race goes through life without having a single original thought. That is to say, they never think anything that has not been thought before and by thousands. ”