When in life do you think it's appropriate to apply the art of selfishness? M, i think i can answer your question with a different book. The courage to be disliked is the best book i've read in the last two years. It shares the philosophy of alfred adler who was a contemporary of sigmund freud. He says that all interpersonal relationship troubles are caused by intruding on some one else's tasks or having your own tasks intruded upon. So saying selfish makes it sound bad. But minding my own business or taking care of my own tasks, i think it's a more digestible perspective on this.