All final spiritual reference is to be the silence beyond sound. The word made flesh is the first sound. Beyond that sound is the transcendent unknown, the unknowable. It can be spoken of as the great silence, or as the void, or as the transcendent absolute.
What I find distinct about gratitude in the wilderness is its simplicity -- the thankfulness I feel here is for what I usually take for granted: my capacity to breathe, move and see ... For the most part, gratitude here wells up unexpectedly, in the quiet corners of the day, over events small and ordinary. Gratitude is the other side of dependence on God: to take anything for granted in the wilderness seems presumptuous, blasphemous. And so, here in these naves of vaulting stone, prayers of thanksgiving begin to edge out prayers of petition.