This is tangential, but I think that the way that the way Lisp does eval with its macros is incredibly elegant. There was a post on HN a few weeks ago [1] about doing symbolic derivatives in Lisp via quotations and eval, and while that was probably old news to most of the HN audience, it was downright magic to me, and the use of eval seemed appropriate.

[1] https://news.ycombinator.com/item?id=18343652