There is no more tragic piece of furniture than a bed, how it falls so quickly from the place we make love to the place we might die in. It is tragic, too, for how it falls so quickly from the place where we sleep to the place where we think ourselves mad. The bed where anyone makes love is also—and too clearly for anyone stuck there because of illness—the grave, as John Donne described it, from which they might never rise.
In vertical life, when you are well or mostly and walking around, pretending to be, the top of your head is the space that the heavens touch. The total area of the top of you is pretty small. You are only moderately airy, then, and your eyes, rather than gazing up, gaze outward at the active world, and it is to this you are mostly reacting. And it is mostly during the night, during dreams, that imagining becomes temporarily expansive and the ceiling air spreads over you, or at least this was, in those days, one magic theory I conjured in bed to explain the relationship of posture to thought.
When you are sick and horizontal, the sky or skyish air of what is above you spreads all over your body, the increased area of airy intersection leads to a crisis of excessive imagining. All that horizontality invites a massive projecting of cognitive forms. When you are so often lying down, you are also so often looking up.