Heinz von Foerster, On Self-Organizing Systems and their Environments, M. C. Yovits, Scott Cameron, Self-Organized Systems.

Assume for the moment that I am the successful business man with the bowler hat in Fig. 2, and I insist that I am the sole reality, while eversthing else appears only in my imagination. I cannot deny that in my imagination there will appear people, scientists, other successful business men, etc., as for instance in this conference. Since I find these apparitions in many respects similar to myself [?], I have to grant them the privilege that they themselves may insist that they are the sole reality and everything else is only a concoction of their imagination (p. 35).