A man's thinking goes on within his consciousness in a seclusion in comparison with which any physical seclusion is an exhibition to public view. - Ludwig Wittgenstein

The temporal immortality of the soul of man, that is to say, its eternal survival also after death, is not only in no way guaranteed, but this assumption in the first place will not do for us what we always tried to make it do. Is a riddle solved by the fact that I survive forever? Is this eternal life not as enigmatic as our present one? The solution of the riddle of life in space and time lies outside space and time.

"383. The argument "I may be dreaming" is senseless for this reason: if I am dreaming, this remark is being dreamed as well - and indeed it is also being dreamed that these words have any meaning."

A tautology's truth is certain, a proposition's possible, a contradiction's impossible. (Certain, possible, impossible: here we have the first indication of the scale that we need in the theory of probability.) (4.464)