Black, White and Those Grey in Between

We tend to catergorize things: there's ten kinds of cookies, twenty kinds of pens, how-ever-many kinds of music. We also categorize humanity.
Here's the thing, what should we set up the categories as? Good and Evil, tall or short, physically or internally?
For now, I'm just going to put it into three categories: optimistic, pessimistic, and those in the gray area.
The optimistic are the lay-back ones, take everything as it is and won't try to desperately change it. The pessimists are the anxious ones, they take everything as "something could be better" and desperately tries to make it better. And because of this, they will prepare everything if they have the chance, and tries to do everything perfectly. Kind of a perfectionist.
Those in the gray is the synthesis of the two, they're able to relax and be tense at various scenes. Perhaps they're the most adoptable ones here. They lack the total bubbly happiness of the optimists but lacks the depression of the pessimists. Maybe they are the ones that are the strongest.
Sometimes I don't even know why I write stuff like this, or how I wrote it.