"Philosophy of love is the field of social philosophy and ethics that attempts to explain the nature of love." There are many different theories that attempt to explain what love is, and what function it serves. It would be very difficult to explain love to a hypothetical person who had not himself or herself experienced love or being loved. In fact, to such a person love would appear to be quite strange if not outright irrational behavior. Among the prevailing types of theories that attempt to account for the existence of love there are:psychological theories, the vast majority of which consider love to be very healthy behavior; there are evolutionary theories that hold that love is part of the process of natural selection; there are spiritual theories that may, for instance consider love to be a gift from God; there are also theories that consider love to be an unexplainable mystery, very much like a mystical experience.