Aristotle said that the man who has everything but doesn't have friends will would not wish to go on living. To a certain extent, that is true. But why? Because friendship cannot be separated from leisure, which in itself, like sustenance and sleep, is necessary to bear a life. We can spend our "leisure time," to be sure, with family and relatives; however, the time spent with friends would be different from that. How so?
Having a family--a wife, children, or your own father and mother, siblings, etc.--still demands from you responsibility; it happens sometimes that even the time we spend with them is necessary, that is, it may become an obligation for a man to bring his family out to lunch every so often, or to a vacation when the children are on a school break. Holidays usually require family calls, etc. And no matter how great and enjoyable that time spent with family, it can be one's greatest treasure, of course--but there is still some obligation to be with them. Though of course there are those who do not care about such things altogether. But that is not the norm.
Yet when it comes to our friends, we are free from all such obligations in the way that we can also not choose to see them, and that absence (momentary or extended does not matter) will normally not break a friendship. Friends can "catch up," this means one can go on running each one's race without having to look back or check on his friend if he is lagging behind. Friends run parallel courses whereas familial ties intersect. This freedom from compulsion or obligation to see (and to have to see many times) our friends brings friendships nearer to leisure.
When we are at leisure, we are at play, we spend time the way we choose to, and if we choose to. The same can be said of friends: friends really for the most part do not do anything but play in whatever form; they can also try new things together or keep on doing what they have enjoyed (like a sport); and they choose to meet when they want to without any party having to feel terrible if the other is not able to make it. Some friends do not see each other for years, yet when they do meet again it seems that no time has passed, that they just saw each other yesterday. A friend does not hold your absence against you. Like a ball or a racket which doesn't mind if you pick it up or play with it too often.
But is this true friendship? Like a game of basketball or checkers? This kind of friendship appears shallow and seems to require nothing from the parties. These are what others usually call "good time friends." It can seem that such friends turn out to be mere acquaintances who "bump" into each other every so often as in parties. This can be said, to be sure.
But everyone knows that in our greatest need the friend is there; he is the one we usually turn to because we sometimes do not want to worry our family who may depend on us. Friends know our deepest secrets. With family, we usually only share our joys. Because we bare our souls to friends, it is the friend who can know us more than any other person. Friends have the ability to "see us"--for who we are, what we are, how we are. Friends in the beginning of their relationships, unlike those who begin to date, do not even have to "know" each other. "The friend," says Nietzsche, "should be a master of guessing and keeping silent: you must not want to see everything." And when vision is unnecessary, knowledge too becomes unnecessary, so does passion--and when these disappear, love can ensue quickly without anything to require it first or sustain it.