“Experience is the best teacher” is an old cliché, but I agree with it. The most important, and sometimes the hardest, lessons we learn in life come from our participation in situations. You can' learn everything from a book.
Of course, learning from books in a formal educational setting is also valuable. It's in schools that we learn the information we need to function in our society. We learn how to speak and write and understand mathematical equations. This is all information that we need to live in our communities and earn a living.
Nevertheless, I think that the most important lessons can't be taught; they have to be experienced. No one can teach us how to get along with others or how to have self-respect. As we grow from children into teenagers, no one can teach us how to deal with peer pressure. As we leave adolescence behind and enter adult life, no one can teach us how to fall in love and get married.
This shouldn't stop us from looking for guidelines along the way. Teachers and parents are valuable sources of advice when we're young. As we enter into new stages in our lives, the advice we receive from them is very helpful because they have already bad similar experiences. But experiencing our own triumphs and disasters is really the only way to learn how to deal with life.