With today marking the 20th anniversary of the House of Representatives vote to impeach former President Bill Clinton, far too many people don’t remember or understand why and how it all happened.

The popular mythology usually goes no further than the idea that “Clinton was impeached for adulterous sex with an intern.” The slightly more sophisticated version is that he was impeached for lying about sex with the intern, Monica Lewinsky. Even with that understanding, most people don’t know why an independent counsel was asking Clinton about sex in the first place.