(3) vs 3 is a both really. In say smalltalk you can call 3 and it would return 3 because semantically it&#x27;s an object where as in lisp it&#x27;s not callable (even if in CL it may be represented as a CLOS object I don&#x27;t know)<p>syntactical ( ) isn&#x27;t actually a procedure call we can see this in (define (id x y) (..)) or (let ((x 3)) ...) in the theoretically pure Lisp semantically it&#x27;s just a leaf in the tree but as part of an if-block in a real language it gets treated as procedure call even if it makes no sense.