Love is Instinct
The love is the feelings to want to leave the person who is important to the self in the future.
(Instinct of posterity preservation)
All lives in addition to the person have the instinct of the posterity save.
The life which doesn't have the instinct of the posterity save has stopped.
First, if thinking that it wants to leave the posterity of the personally, being the most important is called the existence of the personally.
However, to leave its posterity, in addition to making itself and its near person important, the environment in the neighborhood, too, must be improved.
Narcissism → Love to child → Regional love → Home country love → Love of mankind → Natural love → Earth love