One of vital importance
Who is that person of vital importance in the life of every one? Sure, they are parents who are people of vital importance for everyone. Though, in most cases people never tell their parents about everything they have in their live. In most cases a lot of thing of children's life is left behind the curtain for parents. They are other people who know everything.
Those people are friends. They are those people who know everything about one and they are people who are witnesses for every single important event in the life of a person. So, they are people of vital importance and one will feel depressed were those people taken away from his or her life. There are actually never a lot of those people.
Actually, it is possible for one to have only one real friend, all other people are just people you know well and people you have fun with or something. Though, there is always only one friend among them and that one is of vital importance for a person. He or she is the one who can always help you; at least he or she will do the best for this purpose.
It is also a friend a person you will come to in case you have troubles with your parents or with a person you are in love with. And the good friend will never burry you under pieces of advice, he or he is a person who knows when it is a high time to give you an advice and when it is better to remain silent and just listen.