Esse est percipi & verum factum est.

I go into the historical roots of the fundamental issues relating to the "interface theory of perception," concentrating on the sciences rather than on philosophy. The basic ideas have been around throughout historical time. In modern times--I concentrate on a period straddling 1900--they became perhaps "respectable," although interest has dwindled in the recent, post-World War II period. This has been due to an ill-conceived reliance on "physical reality" that has shaped the sciences and philosophy alike. An investigation of the historical development of these ideas serves to shed additional light on various topics treated in the target article (D.D.Hoffman, M.Singh and C.Prakash: The interface theory of perception (this issue)).