Human beings feel affection for that which is lovable, and this can be defined as that which is good, pleasant, or useful. These three feelings are the basis of any friendship, but friendship only exists where such feelings are reciprocal. When both parties do not have the same feelings for each other, it can only be said that one party is well disposed toward the other.
The following conditions must be fulfilled for friendship to exist between two people:
- There must be mutual goodwill (i.e., each party wishes the good of the other).
- Each party must be aware of the other's feelings in this connection.
- This mutual goodwill must originate in one of the causes mentioned above.
Philia, the Greek word usually translated as "friendship" has a much more comprehensive meaning than its English equivalent, as will be seen in the discussion which follows in Books VIII and IX. Philia is the emotional bond between human beings which provides the basis for all forms of social organization, common effort, and personal relationships between people. Obviously there can be a very wide variation in its intensity, ranging from the feelings experienced in a warm and intimate friendship between two individuals to those in such human associations as political states, social clubs, and commercial enterprises. Love in the sexual sense was considered by the Greeks to be a biological phenomenon like hunger or thirst and does not enter into the discussion of Philia.