I've only played with Lisps, so can't quite say I've had the 'enlightenment' experience, but, realizing that "I know how to manipulate lists...and my program is just another list (of lists of lists of lists)" was a bit eye opening.
The regularity of the language makes it so that taking advantage of this is far more reasonable (both a logical thing to do, and something that can be reasoned about) than any other language I've seen (where the closest equivalent would be the eye gougingly bad decision to read in your code as a string and perform string operations to munge it and then 'eval' it. Or, arguably, since this is obviously metaprogramming, reflection, but there it still ends up being something 'special', something very different than just writing a program, and as such is still frowned upon. Lisp is homoiconic, and realizing the ramifications of that made metaprogramming go from a "avoid if at all possible" to just another tool, one that sometimes provides the most elegant solutions, and is reasonable to choose in those situations)
The regularity of the language makes it so that taking advantage of this is far more reasonable (both a logical thing to do, and something that can be reasoned about) than any other language I've seen (where the closest equivalent would be the eye gougingly bad decision to read in your code as a string and perform string operations to munge it and then 'eval' it. Or, arguably, since this is obviously metaprogramming, reflection, but there it still ends up being something 'special', something very different than just writing a program, and as such is still frowned upon. Lisp is homoiconic, and realizing the ramifications of that made metaprogramming go from a "avoid if at all possible" to just another tool, one that sometimes provides the most elegant solutions, and is reasonable to choose in those situations)