 Direct and indirect realists hold different views about the structure of perceptual knowledge. Indirect realists would say that we acquire perceptual knowledge of external objects by virtue of perceiving sense data that represent external objects. Sense data enjoy a special status: we know directly what they are like. So indirect realists think that, when perceptual knowledge is foundational, it is knowledge of sense data and other mental states. Knowledge of external objects is indirect: derived from our knowledge of sense data. The basic idea is that we have indirect knowledge of the external world because we can have foundational knowledge of our own mind. Direct realists, in contrast, say that perceptual experiences can give you direct, foundational knowledge of external  objects.[54]