When trying to understand our own or the other people's behaviour, we tend to over-simplify things. We use one or two adjectives to sum each other up. We think of one friend as having a generally hopeful and positive outlook, while another friend is considered pessimistic and negative.
Of course, in reality, none of us is so easily defined.
The truth is that we are all made up of inconsistent and contradictory characteristics; we can be serious and reliable with our colleagues at work, but in our personal relationships at home we are adventurous thrill-seekers with other friends.
So can people be neatly dividen into personality types? Or do we alter our personality according to the differences in our changing moods and situations? Perhaps the idea of a fixed personality is just a meaningless misconception. Maybe we can never truly understand ourselves or other people.