Like the concept of the assemblage, the body without organs is much written about, but unlike the assemblage there are no specific schools of thought associated with the body without organs, much less any agreed definitions. As such, it tends to be used in a very vague manner, with most accounts of it ignoring its practical dimension and instead focusing on its aesthetic (Artaud) and philosophical (Spinoza) origins. However, Deleuze quite explicitly positions the assemblage as a contribution to an understanding of behaviour, so the purely philosophical accounts of the body without organs that give no account of how it can be used analytically are not helpful in my view. I demonstrate that the practical conception of the body without organs is an effective way of understanding the concept. I use the example of George Mallory's attempt to climb Everest to illustrate this point. I argue that if we focus only on the symbolic attainment of being the first person to climb the world's tallest mountain and consign the actual act of climbing to the realm of mere entry price, then we effectively destroy the assemblage by rendering it teleological. Now, one might think that this means one should balance the equation by focusing on the bodily dimension of the climb, and certainly that is the direction we need to take, but to do that we need to conceive of a space where that physical dimension can be registered in something other than purely biological terms. If, as Spinoza and after him Deleuze have argued, we do not know what a body can do, it is because we do not have the conceptual means of capturing and expressing its capabilities. We can record its achievements, but we cannot map its capabilities because the body seems always to be capable of doing more than anyone thought possible. Until 1953 when Hillary and Norgay reached the peak of Everest climbing Everest was generally regarded as impossible. A view that was reinforced by the dozen or so failed attempts, not to mention the many deaths occasioned by those attempts, that preceded Hillary and Norgay' success. This is why Mallory's insouciance in 1923 was so captivating. His answer 'because it's there' shrugged off the one thing that was standing in the way of the conquest of the peak, the conviction that it was impossible. It also explains why his answer passed into history.