We tend to believe that we are right in what we think we know. 

But “what we know” isn’t always right.

Some things we used to “know” that aren’t so.

1. The earth is the center of the universe.
2. The earth is flat.
3. The sun revolves around the earth.
4. Disease is caused by humours in the blood. The cure is to drain some blood out of your body.
5. Humans only use 10% of their brain.
6. Cracking your knuckles causes arthritis.
7. Eating carrots will improve your eyesight.
8. Women are intellectually inferior to men.