Locke's attempt to give a priority to the physical world, and hence to the body, was laudable. One problem: to do this, he had to resort to a representational theory of knowledge.
Representational Theory of Knowledge: Your mind is like a little movie theatre. There's a projector which shows you a movie of the outside world. You are not "seeing" that world directly; rather, your senses are assembled into a coherent whole, and shown to you on this little screen. Your knowledge, then, is representational, in that you know an image of the world, and not the world itself.
So, what's the problem? Well, two thinkers that followed Locke showed us the problems with this.
Thinker #1: George Berkeley
Berkeley took Locke very seriously when he said that all our knowledge comes from sensation. He also took the representational theory of knowledge seriously. And he noticed that we didn't necessarily need to have the objective world hooked up to those representations. What if no one was perceiving something - does the world exist? You know, if a tree falls in a forest, and there's no one there to hear it, does it make a sound? That's Berkeley's problem.
And his conclusion: No, there's no world apart from our perception of it. To Be Is To Be Perceived. Reality just resides in perception. Of course, he thought that God always perceived the world, so everything was ok. But still - where is the physical now? Where is body now?
Thinker #2: David Hume
Hume also took Locke seriously when he said that all our knowledge comes from sensation. He thought, if that's true, we should be able to take anything we consider to be knowledge, and trace it back to sensations of the physical world.
Can we do it? Hume said, no. There are things that aren't traceable in this way. For instance:
This last one is the problem for empiricism. Do we ever "see" an external object, or just the sensations? How do we know the external object is there? This could be the Matrix, in which we are just being fed impulses to make us believe in an external world.
And what about space? Newton had argued for "absolute space", a container in which things existed, but which would exist whether there were things there or not. Hume says, how would we know? How could we perceive this thing which does not give off any sensations at all?
The result: This attempt to recover the physical world (and by implication, the body) fails. At this point we still do not have a good account of how the body might exist in the world, and it not be just an inert object. Furthermore, we don't have an account of our own bodies, despite the attempt to take sensation seriously. We still just end up being disembodied minds.