I need some motivation to do that.

| I didn't have an intent to get an absolutely correct description of
| variables evaluation mechanism but just a somewhat simplificated model that
| able to lit a some light on the topic for a person that is not a Lisp
| expert.

  This is the opposite of motivation for me.  Some of us here actually spend a
  lot of time trying to get things absolutely correct, only to be met with a
  strong desire to get it less than correct and highly confused.  This is not
  rewarding.

| But, after looking in HyperSpecs and in proposal that has been mentioned by
| Kent Pitman (thank you, Kent, it is very useful), I still don't understand
| what 'is just plain wrong' in my message.

  Then you do not understand what you wrote, either.  

| So, I hope, you will help me to understand in what.

  I no longer know where you went wrong, so I cannot help you.

--
Erik Naggum, Oslo, Norway

Look at these examples:

(let ((behaves-essentially-as-static 0))
  (defun foo ()
    (incf behaves-essentially-as-static)))

(defun make-adder (increment)
  (lambda (val) (+ val increment)))

(defun test-adder ()
  (let ((f1 (make-adder 3))
        (f2 (make-adder 7)))
    (list (apply f1 2) (apply f2 2) (apply f1 5) (apply f2 5))))

Now try first guessing what these two function calls will return:
(list (foo) (foo) (foo))
(test-adder)

Typo? I think you meant one of the following alternatives, yes?

        (defun test-adder ()
          (let ((f1 (make-adder 3))
                (f2 (make-adder 7)))
            (list (funcall f1 2) (funcall f2 2)
                  (funcall f1 5) (funcall f2 5))))

        (defun test-adder ()
          (let ((f1 (make-adder 3))
                (f2 (make-adder 7)))
            (list (apply f1 2 '()) (apply f2 2 '())
                  (apply f1 5 '()) (apply f2 5 '()))))

        (defun test-adder ()
          (let ((f1 (make-adder 3))
                (f2 (make-adder 7)))
            (list (apply f1 '(2)) (apply f2 '(2))
                  (apply f1 '(5)) (apply f2 '(5)))))

-Rob