Full Idea
The Ego can be conceived only through itself and this is why we cannot grasp the consciousness of another (for this reason alone, and not because bodies separate us).
Gist of Idea
We can never, even in principle, grasp other minds, because the Ego is self-conceiving
Source
Jean-Paul Sartre (Transcendence of the Ego [1937], II (D))
Book Reference
Sartre,Jean-Paul: 'The Transcendence of the Ego' [Routledge 2004], p.37
A Reaction
Interesting. This makes telepathy a logical impossibility, and the body the only possible route for the communication between two minds. But, is Sartre is right, how do bodily events penetrate the inturned world of the Ego?