But he can describe quite well, in spite of this, the peculiarities of the phantom leg, for example its curious motility, and if he treats it in practice as a real limb, this is because, like the normal subject, he has no need, when he wants to set off walking, of a clear and articulate perception of his body: it is enough for him to have it 'at his disposal' as an undivided power, and to sense the phantom limb as vaguely involved in it.