Epistemological realists have long struggled to explain perceptual error without introducing a tertium quid between perceivers and physical objects. Two leading realist philosophers, Thomas Reid and Everett Hall, agreed in denying that mental entities are the immediate objects of perceptions of the external world, but each relied upon strange metaphysical entities of his own in the construction of a realist philosophy of perception. Reid added ‘visible figures’ to sensory impressions and specific sorts of mental events, while Hall utilized an array (...) of ways that he maintained properties may participate in the world. This paper assesses each realist's attempt to explain perceptual relativity and illusion without contradicting either the science of his time or the structure of common sense. (shrink)