This friend, I wonder if you have read Dale Carnegie’s The Weaknesses of Human Nature. There is a famous saying by Socrates in it. This is the sentence. I borrowed the original words from Carnegie’s book, people’s concepts, Things are changing all the time. What I thought was right twenty years ago seems to be wrong now. Even as I studied Einstein's theory, I became skeptical. Twenty years from now, I may not believe what I wrote in this book. Now I am not as sure about anything as I used to be. Socrates repeatedly told his disciples: "The only thing I know is that I know nothing." I hope this helps you.