The point just made may be explained as follows.
Since no two thoughts can occur simultaneously, the only relation between any two objects in consciousness must be represented by the observer of them.Sensorial perceptions occur by means of a psycho-somatic apparatus to which the perception is attributed, by identification, as subject. But the supposed subject is itself an object, so that the two objects remain quite unrelated except via the observer, who alone observes them both.
The transcendence of duality, therefore, is represented simply, and exclusively, by the observing consciousness.
The Observer is, of course, just the consciousness in which objects appear.