From << The God Delusion >> av Richard Dawkins
P49: The fact that we can neither prove nor disprove the existence of something does, not put existence and non-existence on an even footing.
From << You Are Not So Smart >> av David McRaney
Chapter 15: The argument from ignorance
P99: Lack of proof neither confirms nor denies a proposition. Is there life on other planets? We can't say yes or no just because it hasn't been discovered yet. No matter how you feel about the question, you would be incorrect to assume the lack of evidence proves your assumption. At the same time, you can't just live your life so open minded you never accept proof.
From << Rationality and the Pursuit of Happiness >> av Michael E. Bernard
P243: He (Albert Ellis) also believes that it is irrational to obsess about questions of death and our place in the universe because of the unavailability of ultimate answers. In addition, Ellis believes that people's search for existential answers tends to be obstructed by their psychological "need" (which Ellis calls ego) to have a special place in the grand scheme of the universe.
However, as Ellis notes, the universe does not care one way or another for our "immortal souls." Rather than desperately searching for how you belong to some universal entity or process, it would be more productive to concentrate on accepting yourself without demanding that your self, or self-definition, or happiness can only be attained when your place in the universe is understood or guaranteed.