Excel helper(s)

I am reading a book on VBA and am confused over a point the author is trying
to make over controls.

With Form controls one can write a simple Sub procedure and assign it to the
button no problem. This I understand.

For ActiveX controls the author states...'If you try to create an event
procedure for an ActiveX control before the control exists, and you try to
reference that in your code, you will get compiler errors, so you have to
create the event procedure programmaticaly'.

What does this mean exactly?

If I place an ActiveX button on the worksheet and double-click then I can
add my code in the class module that will be of the type:

Private Sub CommandButton1_Click( )

There is no problem with this as I see it. Is the author's point that if you
add an ActiveX control using VBA then you must write the event procedure in
the VBA code too? In other words, you can't write an event procedure first
and then create the ActiveX control laterbecause they won't reference each
other?

The author does offer an example of this method and, whilst I understand the
VBA code, I don't understand in principle what the key idea is.

I am hoping that somebody on this list has better insights for this layman.

Regards

Alex