The “non-dupes who err” means that anyone who is not in love with his unconscious errs. That says nothing whatsoever against past centuries. They were just as much in love with their unconscious as the others and so they did not err. Simply, they did not know where they were going, but as regards being in love with their unconscious, they certainly were! They imagined that it was knowing (la connaissance) because there is no need to know that one is in love with one’s unconscious in order not to err. One only has to offer no resistance, to be its dupe. For the first time in history, it is possible for you for you to err, namely, to refuse to love your unconscious, since in short you know what it is: a knowledge, a knowledge that pisses you off. But perhaps in this impetus (e-r-r-e), you know, this thing that pulls, when the ship is riding at anchor – it is perhaps here that we can wager on rediscovering the Real a little more in what follows, to perceive that the unconscious is perhaps no doubt discordant, but that perhaps it leads us to a little more of this Real than this very little of reality which is ours, that of the phantasy, that it leads us beyond.
— from Seminar XXI: Les non-dupes errent, by Jacques Lacan
— from the Desk of the Unconscious