The bible and the philosophy explain that there are many types of friendship: there is a first type that arises from the need and the opportunity, is the friendship born of a shared goal. While the common goal subsisting also the friendship.
A second type of friendship is born from the pleasure of see ourselves reflected in the others, and this kind of friendship is related to Philia, a Greek word which means love of the soul.
Keep in mind that these two forms of friendship arise from the desire of happiness that is the natural desire of the soul. The desire for happiness is known as sensitive appetite and is a selfish desire. These two forms of friendship are utilitarian forms of friendship, because we give and receive proportionately from our friends and this refers to justice.
Finally there is the friendship based on the excellence of the friends, this kind of friendship is born from the desire for the good (desire for improvement and taste of wisdom) and the Agape, the spiritual love, the love of the spirit.
The desire for the good is known as intellectual appetite, is oriented to the universal good and not to the particular good as the desire for happiness.
“There is no greater love than to lay down one´s life for one´s friend” means to give the best and most excellent that we have, this love is not a selfish love that seeks only the own happiness but a good and demanding love that seeks the good of all, " the common good" , this love also means " love your neighbor as yourself."
The idea of the common good, which is different from the idea of the own happiness, born from this type of friendship.
 This form of friendship is not associated to Justice but to Mercy and involves not only sympathy but also empathy, that means to put ourselves in the place of the others.
This form of friendship puts us in perspective the clear difference between morality and ethics, between soul and spirit; between the pursuit of the own happiness and the "happiness of all." When "everyone is happy”, "we are all one."
The unity of minds and hearts, pure love, the true friendship and the common good are inseparable concepts.