This was one of the most important parts of the Sequences for my subjective well-being. We're not getting into metaethics proper yet, but specifically, Reductive Reference made it click for me that it was not the case that the moral terms I used in the past fail to refer. I stopped thinking, "That stuff seems like it was illusory," and started thinking, "I experienced that moral stuff in the past; if that moral stuff isn't fundamental, then what exactly was that moral experience in terms of what I do know to be fundamental?" It's very nice to get away from a state of mind where you think that what you thought you valued cannot be located in the world.