_Why_ was the provision inserted?
4.

How is it carried into practical effect?
Some of the provisions should be so thoroughly committed to memory that at any time they may be accurately quoted.

The ability to quote exactly is an accomplishment well worth acquiring.
After you have got through with a line of investigation it is a good thing to make a synopsis of the conclusions reached.

Hints are given at appropriate places as to how this may be done.

But the doing of it is left to you, that you may have the pleasure and profit resulting therefrom.
Finally, without fretting yourself unnecessarily, be possessed of a "noble dissatisfaction" with vague half-knowledge.