In trying to control an observed 'I', you must remember that it is something that thinks, and feels and moves—that is, each representation of it in each center is different. The control of the human machine is difficult therefore because everything that is formed in it psychologically —namely, as an 'I'—is represented in three entirely different ways, that seem at first sight unconnected.

We should observe not only vaguely our emotional state but the words or gestures or expressions that accompany this state—and this means to observe two centers.