Lisp was the Python of its day, but more so - one of very few high level, garbage collected languages that were reasonably widespread. In Lisp you could explore

Lisp was the Python of its day, but more so - one of very few high level, garbage collected languages that were reasonably widespread. In Lisp you could explore data representations and novel control flows (search algorithms, nondeterminism, etc.) without getting bogged down in bits, bytes, and storage management, and s-expressions provided (and still provide) a reasonable middle ground representation for encoding complex structured data that both humans and machines can deal with.