Toward the beginning of Confessions, his famous memoir about his journey to the Christian faith, Augustine says this.  "You [that is, God] had then conceded to me that, should I have demonstrated that there was something above our spirits you would have recognized that such is God, if there was nothing found above that.  And I, accepting your admission, said that it were enough to make that demonstration.  Because, if there is something more excellent, that something is God, and if there is not, then already that same truth is God.  Both in the one case and the other, therefore, you cannot deny that God exists."
     What is Augustine saying?  Whether we say there is nothing greater than us, or whether we say that there is not something greater than us, we end up affirming the same thing:  there is a greater truth than we, a truth that we, though we think we define it, we only do so on the basis of the fact of ourselves, which becomes in itself, our ultimate truth.  We cannot live without a--the--truth.
     So ask yourself:  is it really us?