Laziness & transparency
MISC is a lazy, or non-strict, language. This means that values are evaluated by need, and allows for MISC to have no special forms and support infinite data structures. Such as all the positive integers.
And it is possible to redefine if without any trouble, because it is not a special form.
Another aspect of MISC is that it is referentially transparent, which means that an expression can always be replaced with its value. That is, [+ 2 3], 5 and indeed [+ 1 [* 2 2]] are all interchangable. This is the reason lambda and let require data as arguments, because[lambda [x:10] [+ 1 2]] is equivalent to [lambda nil 3].