>>21
I think it can be summed up in that very few languages can be described as homoiconic, and even fewer of those are truly so in the sense that Lisp is. It's not enough that programs be manipulable as data, but for it to be possible for the program to encode it's own understanding of itself in a simple manner, syntax be damned. Given how far this plays into the whole metaprogramming aspect, I would have to agree with what >>2,14 had to say in that any hypothetical language that shares enough qualities with Lisp in that it achieves these properties is essentially Lisp.