From 1.4.9. – Mysticism and Morality – Pt. 1:

Now, you see, I’m not talking about a philosophy, I’m not talking about a rationalization, some sort of theory that somebody cooked up in order to explain the world and make it seem a tolerable place to live in. I’m talking about a rather whimsical, unpredictable experience that suddenly hits people, and it includes this element of feeling the total harmoniousness of everything.