David Gale's lecture

From Lacan’s point of view, fantasies have to be unrealistic because the moment, the second that you get what you seek you don’t / can’t want it anymore. In order to continue to exist, desire must have its objects perpetually absent. Its not the “it” that you want it’s the fantasy of “it”. So desire supports crazy fantasies.

This is what Pascal means when he says that we are only truly happy when daydreaming about future happenings or why we say the hunt is sweeter than the kill or be careful of what you wish for, not because you will get it but because you are doomed not to want it once you do. So the lesson of Lacan is that living by your wants will never make you happy. What it means to be fully human is to strive to live by ideas and ideals and not to measure your life by what you have attained in terms of your desires, but by those small moments of integrity, compassion, rationality even self-sacrifice because in the end, the only way we can measure the significance of our own lives is by valuing the lives of others.