Freud comes to Charcot's clinic. He sees interns giving women inhalations of amyl nitrate, and they then bring them, intoxicated, for Charcot to see. The women adopt certain postures, say things. They are listened to and watched, and then at a certain moment Charcot declares that this is getting ugly. What we have here, then, is a superb gadget by means of which sexuality is actually extracted, induced, incited and titillated in all manner of ways, and then suddenly Charcot says that that's enough of that. As for Freud, he will ask why is that enough. Freud doesn't need to go hunting for anything other than what he's seen at Charcot's house. Sexuality was there before his eyes, orchestrated by Charcot and his worthy aides.
That 'suddenly' will go on for years if you let it.
Michel Foucault tells good jokes in Power/Knowledge, his big book of interviews.