He compares linguistic expression to projection in geometry. A geometrical figure may be projected in many ways: each of these ways corresponds to a different language, but the projective properties of the original figure remain unchanged whichever of these ways may be adopted. These projective properties correspond to that which in his theory the proposition and the fact must have in common, if the proposition is to assert the fact.
Self-expression or how one manifests in the world is comparable to projection in geometry. Your origin, axes of the n-dimensional space, transformations (or the lack of) through time and space and finally consciousness defines who you are.
There's a world out there that only you have access to.
