We tend to believe in the modern secular world that if you tell someone something once, they'll remember it. ... Religions go, "Nonsense. You need to keep repeating the lesson 10 times a day. So get on your knees and repeat it." That's what all religions tell us: "Get on your knees and repeat it 10 or 20 or 15 times a day." Otherwise our minds are like sieves.
The powers of the mind should be concentrated and the mind turned back upon itself; as the darkest places reveal their secrets before the penetrating rays of the sun, so will the concentrated mind penetrate its own innermost secrets.
It is perhaps just dawning on five or six minds that physics, too, is only an interpretation and exegesis of the world (to suit us, if I may say so!) and not a world-explanation.
But in physics I soon learned to scent out the paths that led to the depths, and to disregard everything else, all the many things that clutter up the mind, and divert it from the essential. The hitch in this was, of course, the fact that one had to cram all this stuff into one's mind for the examination, whether one liked it or not.