What's the difference between sunlight and moonlight? Sunlight chases all darkness away. Moonlight somehow increases the contrast. It makes us more able to see shadows to which we were previously oblivious. Full Moon is associated with horror because it somehow reveals much that might otherwise have been hidden from us. Sometimes, the things that we are most keen to keep hidden away, are the forces and factors of which we feel most afraid. Yet what you become able to see brings nothing but benefit.
Two plus two equals four. You know that. You established it, to your satisfaction, a long time ago. It is a fact you don't have to think about. Any time, anyone invites you to do this sum, that's the answer you are going to give. All well and good. But are there other questions which may seem to have similarly indisputable answers, yet which actually deserve further consideration? Extenuating circumstances apply to a sensitive situation. The only way to know how things are adding up is to actually do the math.