If the words the cogito 'on', 'through', etc., are to retain any meaning, it is in virtue of my working on a perceptible or imaginary triangle, that is to say, one which is at least potentially situated in my perceptual field, orientated in relation to 'up' and 'down', 'right' and 'left', or again, as we pointed out earlier, implied in my general grip upon the world.