I'm just throwing this out here, because I've consistently noticed this phenomena. Typically a bit over halfway through, or so, of meditating my mind becomes quite excited with thought, fantasy (not necessarily sexual per se), or even anger. I've noticed this pretty consistently, and it strikes me as odd that the first part of my meditation session is quite a bit more calm than the second (or so). Has anyone else experienced this or can relate to this? I conjecture that perhaps during the first part of meditating that my mind calms, and that then releases an up-welling from a deeper part of my mind that I experience in the later portion of the session, but I'm not sure. Anyone care to opine?