Mutual emotional inclination, which arises from a perfect conformity to hear and the consequent mutual readiness to reveal the innermost aspects of their personality.
In the Bible friendship it is regarded as the perfect form of the gratuitous, characterized by the participation and the unconditional solidarity. God is the friend of man, as revealed in a special way to those who have chosen as cooperators determinants of salvation history. Aristotle admits three kinds of friendship that are divided in turn by numerous shades: one that is based on pleasure; one that is based on the interest and one that is based on the moral good.
(Ethics 1156b, 7).
Friendship is essentially a mutual love between similar: is a deal with others like ourselves. "The love with which one loves himself is shaped like a friendship root: in fact we have friendship for others as we behave with them as to ourselves."
Friendship is distinguished both by love and charity. There is no distinction between friendship and love and not love to any one can call friendship: "I do not love anyone but only accompanied by benevolence has nature of friendship: that is when we love one to other with kindness. If we do not want good to the things you love, but their own good same good we want it to us, as when we love the wine or other things like that, you do not have love of friendship but of lust. It is ridiculous to say that one has friendship for wine or for the horse. Indeed, for friendship is not enough even benevolence but requires mutual love, because a friend is friend to his friend. And this mutual good is based on some commonality".
But there is also a distinction between friendship and love. In fact, the scope of friendship is greater than that of charity, so that it can be said that charity is a friendship subspecies: "Charity is man's friendship with God primarily, and then with the beings that him belong ", and among the things that belong to God first of all with the men, but then also with the angels. But only the good man can have fellowship with God and this friendship demands obedience.
Friendship is all the power of God towards His creatures endowed with intelligence. "And 'the essence of friendship that the lover wants the beloved desire is fulfilled, because in fact wants the good and the perfection of him; and therefore it is said that friends are one heart (Sallust, Chapter . 20). Now, we have seen that God loves his creature, and all the more he loves as much as taking part in its goodness that is the first and main object loved by Him. Therefore, he wants us to have fulfilled the desires of the rational creature, which of all creatures participate in the most perfect way to divine goodness".
The friendship is essentially based on the communion and sharing. So they give so many types of friendship, as there are types of communion and sharing. St. Thomas lists four types of friendship: friendship between blood relatives (amicitia patris et filii et aliorum consanguineorurn) based upon the natural communion due to the same seed; friendship between "workers", based on economic sharing, as participating in the same industry; friendship between fellow citizens, as participating in the political life itself: Finally friendship between believers, including Christians, "is the divine communion by which they are part of the body of the Church or actually or potentially." The last is the friendship of charity (amicitia Caritatis) and you must also to enemies.
For friendship it takes a certain equality between the two terms: only a certain equality, not a perfect equality; amicitia not requirit aequaliatem aequiparantiae, sed aequa1itatem proportionis. Too great a disproportion between the two terms cancels the friendship and makes it impossible. At the very least an affinity analog. And between man and God, according to St. Thomas this affinity (analogy) there, and so can be said that "man naturally loves God of love of friendship, even more than himself.".
The only equality is not enough: not enough that these are two identical notebooks, two identical plants: it is necessary that the two terms would establish some communication, an exchange. From this it is that man cannot treat as friends the animals or things, and even the virtues or good qualities: "In fact, do not communicate in our human life nor as being or how to action, so we cannot feed in them the goodwill that you have a friend".