Full Idea
The perceptual 'something' is always in the middle of something else, it always forms part of a 'field'.
Gist of Idea
Perceived objects always appear in a context
Source
Martin Heidegger (Being and Time [1927], p.4), quoted by Kevin Aho - Existentialism: an introduction 3 'Perceptual'
Book Reference
Aho,Kevin: 'Existentialism: an introduction' [Polity 2014], p.40
A Reaction
Sounds like our knowledge of electrons. Nice point. Standard analytic discussions of perceiving a glass always treat it in isolation, when it is on an expensive table near a brandy bottle. Or near a hammer.