If you can regard higher-order functions as
unnatural, then you can regard Common Lisp's
semantics as natural. That's the real lesson
of the Gabriel/Pitman paper cited earlier in
this thread. By the way, that paper was not
subject to normal peer review; it was political
from the start, and its conclusion that the
advantages and disadvantages of Lisp-1 and
Lisp-2 are comparable was pre-ordained.
To reach that conclusion, they had to count
at least one of the arguments against Lisp-2
as an argument in favor of Lisp-2. I won't
spoil your fun by explaining this; it's obvious
if you read the paper carefully with an open
mind.