This is an interesting topic I think - I think these emotional states are highly prevalent and when you're in the squall of them, they can be very difficult to get out of. I often have "rashes" of doubt overcome me - don't you? Is there a person on the planet who has lived entirely doubt free? I doubt it! Then we come to delusion! Which I think is almost the blindly optimistic 'twin' to doubt. Quite often it will take an external viewpoint to help us out of these two states - a new perspective on the troubles (doubt) or the dreams (delusions) we are caught up in. So here's my perspective on the matter - I hope it gives you some food for thought about what your doubting in your life, or what you might be blindly optimistic about.