1.3.2 LISP Evaluates Everything

LISP evaluates complex arguments in order to apply an operator. Actually, LISP tries to evaluate all its arguments, even simple ones like ‘8’ and ‘3’. What does it mean to evaluate a nubmer? The answer, in LISP, is that numbers evaluate to themselves. That is, any time LISP tries to evaluate ‘8’, the answer is always ‘8’; when it tries to evaluate ‘3’, the answer is always ‘3’.

-> 8
8
-> 3
3
->

In sum, numbers are really s-expressions too. They are just very simple ones that always evaluate to themselves.