The essence of human life is contact with stimuli of various kinds. These include relationships with other people, weather conditions, stressful situations, joyful situations, unpleasant situations. Some of these we accept, some we aspire to, and from others we would prefer to stay as far away as possible. Sometimes anxiety arises in relation to certain situations and it too is, to some extent, natural and evolutionarily necessary. After all, if we did not feel fear at the sight of a fire, instead of running away, we would approach the throbbing fire with a smile to warm ourselves by it.