I’d go with etymology. Take something you wrote (say, the sentence above that you just wrote) – and crack upon an etymology website and see where the words came from and REALLY wrap your mind around how the words transformed and changed over time to get all the nuances of meaning they have today – and get a feel for what meanings might be hidden within the language you already use that is obscured.
Oh hell yeah. I love that kind of stuff. Irrationally exciting is about the best way to describe it. It feels like possessing a secret viewport that stretched backwards through time and forward into the future and each cast their lights and shadows upon today, and my brain and feels are all like, “pop pop pop pop pop”. I get giddy inside tongue emoticon