Second, icons do not contain enough information. You cannot generally tell from an icon what you are doing. Suppose all street signs consisted of icons. Or suppose we used icons in the public library. The Wind in the Willows is easy enough to represent, I suppose.
Icons add to confusion, offering little in the way of relief or simplicity in return.
It is an apparently simple device. But it is evil, pure evil. If we analyse what is involved in the operation of a mouse, we can see instantly that it requires the user to master a series of high-skill motor and interpretive operations. The idea is that the position of the mouse corresponds with the position of a pointer on a screen. Well - the position of the mouse doesn't exactly correspond, since you can lift the mouse from the pad and move it without moving the pointer.