When Russell describes his perception of the table, he points out that we often confuse the way things appear to us with the way they really are. He notices that our perceptions are actually mediated by sense data — that we are inferring the nature of reality, not seeing it directly.
This insight is closely related to the explanation between perceptual illusions. Take a few minutes to have a look at the following illusions:
1- The wagon wheel effect: http://www.michaelbach.de/ot/mot-wagonWheel/index.html
2- Shephard’s “turning the tables” illusion: http://www.michaelbach.de/ot/sze_shepardTables/index.html
3- Change blindness (click on any of the pictures at the bottom): http://www.gocognitive.net/sites/default/files/change_blindness.v.0.93_0.swf
Illusions reveal how our perception of the world is different from the way the world really is. What do you think this can tell us about epistemology? How can we recognize illusions? How do we correct them? What is our best source of knowledge?