A simple guide to GIT using spatial analogies (scroll down)

    To visualise this, it’s simplest to think of the
    state of your repository as a point in a high-
    dimensional ‘code-space’,  in which branches are
    represented as n-dimensional membranes, mapping
    the spatial loci of successive commits onto the
    projected manifold of each cloned repository.

Oh, of course, it's so clear to me now! -_-