Simply put, it means that a sane person cannot hold two conflicting ideas or perceptions in his (or her) brain at the same time.

You cannot think of yourself as both clever and stupid at the same time. One of the conflicting ideas (cognitions) will have to go. To reduce dissonance you might edit memories, censor your sensory perception, re-focus attention - until one of the two conflicting ideas are removed. You will see / hear / feel / smell / remember things only as long as they are congruent (in line with) the belief you choose to accept.

Seeing is not believing - but rather: believing is seeing: We can only see what we already believe.
I tripped across this concept yesterday and woke up this morning with a whole new understanding of the world.

No. Not that "Meaning of life, the universe and everthing" type undertanding. Rather, a better understanding of why people think and do the things they do. The knock-on effects are quite amazing.

For example, it explains why a smile is a better selling tool than technical competence. How can you distrust a person that you like? So Technical Joe has to go.

So I was wondering if anyone felt like exploring cognitive dissonance and how it affects our lives. I know it sounds heavy but it could be fun and rather useful.