From Lacan’s Seminar X: Anxiety pg 306:
Although ordinarily the fantasies of the obsessional subject, whatever level of luxuriance they may reach, are never executed, it does happen all the same that, through all sorts of conditions that postpone their enactment more or less indefinitely, he realizes his desire. Better still, it does sometimes happen that others may clear the obstacle out of the way for him.
The point Lacan is making in his analysis of the character structure of neurotic obsessives is that they don’t want to get what they want. This doesn’t mean they don’t want the object, only that they don’t want that desire to be enacted.
The insight here concerns the disavowed enjoyment (jouissance) which being wilfully deprived or finding reasons to postpone can generate. As long as I don’t get my object, I can imagine a world of fulfilment which my eventual encounter with that object will open up. This jouissance is at risk if my desire is realised because I will be confronted with the fleeting, partial and fragmented character of that fulfilment.
In this moment lurks a truly terrifying prospect: what if all objects are disappointing in this way? Better to rely on a network of habits, rituals and fantasies which continually defer this moment of encounter with the real, rather than risk the viability of desiring as such. It’s better to blame circumstances or personal faults, propping up a distance from fulfilment, than it is to really act in relation to desire. The obsessional getting what they want, as indicated in the passage above, more often happens in spite of rather than because of their agency.
