Socrates famously said that the unconsidered life is not worth living. He meant that a life lived without forethought or principle is a life so vulnerable to chance, and so dependent on the choices and actions of others, that it is of little real value to the person living it. He further meant that a life well lived is one which has goals, and integrity, which is chosen and directed by the one who lives it, to the fullest extent possible to a human agent caught in the webs of society and history.
Socrates liked to tease his interlocutors by saying that the only thing he knew was that he knew nothing. There is a deep insight in this, for the one thing that is more dangerous than true ignorance is the illusion of knowledge and understanding. Such illusion abounds, and one of the first tasks of philosophy