Bodily Investigation

During the meditation practice today,I had the idea that "if only my back weren't so tight, I could practice better". This is a view that comes from believing that the mind is trapped in something called "the body", as though the body were a kind of metaphorical container. But if one really examines, using modern science, what gives rise to the feelings of the body, it turns out that there is no container whatsoever.
  I feel a sharp pain in my back or lower side, and I then have the thought, "If I shift it this  way, it will become more balanced", or "this would relieve it". So I imagine taking a tight thing and loosening it to make it more spacious. The more I engage in this process of trying to "fix" my posture to an ideal position,the more I lose sight of investigating the mind. I start to cultivate the idea that the body is an obstacle to meditative practice that needs to be fixed, conquered or tamed. This might be analogous to how civilizations view nature. It seems to be intuitively correct, but is it?
  The body might feel relieved for a little while, but soon enough, "relief" becomes another habitual feeling. I then search for a better sensation, such as a cool drink on my mouth. Is the "body" ever "filled completely" or even satiated? For a little while, it seems this way, but actually the body cannot be filled because it's a habitual concept. As long as I cherish the body as an enduring object, I give into feelings of dissatisfaction and wanting to fill the body with pleasure.
   There isn't really anything to do with the body. One must be confident in the method of trying to find the mind that contemplates body or cherishes the idea of body. It is this mind that is the real "object" of meditative investigation, even though it can never really be an object whatsoever.