Thus, he comes to the conclusion,
The whole experience was but illusion.,
Because, he argues -- razor-witted --
That cannot be which is not permitted.
***** Galgenlieder – Morgenstern (trans.W. Kaufmann)
And, now, another quote. But this time from someone you are more likely to recognize.
Science is a willingness to accept facts even when they are opposed to wishes. Thoughtful men have perhaps always known that we are likely to see things as we want to see them instead of as they are, but thanks to Sigmund Freud we are today much more clearly aware of "wishful thinking." The opposite of wishful thinking is intellectual honesty -- an extremely important possession of the successful scientist. -- B. F. Skinner,Science and Human Behavior, (New York: Free Press, 1953) p.12
It’s easy to preach.
To examine these issues further, see A Critical Review of B.F. Skinner's Philosophy