One of the more dense things that each of us will encounter in our lives is the juxtaposition of what we know against what we reckon we know. The cause why this makes difficulty is since our own perception of our own knowledge (i.e. what we reckon we know) frequently exceeds what we really know by a significant margin. Furthermore, this phenomenon seems to expand as our knowledge base increases. This produces the unfortunate effect of making an intellectual elite that over-estimates the depth and scope of their own knowledge by many orders of magnitude. More information: more info