Take a look at this great optical illusion. Stay with it for a few moments, and then there is a wonderful ‘aaaah…’ moment.
I don’t want to turn this into a philosophical treatise, but it shows – as all optical illusions do – how wrong our first impressions can be, and how there can be a completely different way of looking at things that hasn’t occurred to us. On the other hand, it shows how the ‘solution’, the truth of the situation, is usually something that makes complete sense to us in the terms of the knowledge that we previously had – otherwise it wouldn’t actually be a solution for us.
So an illusion like this momentarily undermines our hold on truth, and yet reinforces the hold that truth has on us. The experience of being deluded or mistaken isn’t actually an argument for scepticism, because you can only know you are mistaken if you have some new purchase on the truth.