It is a gesture given in sympathy, or a mark of friendship.
Kisses tie human hearts together.
They express our deepest most inner feelings. When we see children and little babies we often want to reach out and kiss them because of their innocence and sweetness. When there is a tragedy and we see others in sorrow and pain we want to show them we care. When we see joy and beauty and our hearts are filled with happiness, it is a natural response to want to reach out and kiss someone. As a symbol of love it is an inexpressible sentiment given by two who are connected by both heart and soul.