Shadow and Substance; how to tell the difference?

In this picture of a backyard epiphyllum, the difference is clear. I can tell the shadow from the flower.

When I was in high school, I had a treasured copy of a book called Have you read 100 great books? It was paperback and largish, about the dimentsions of Time magazine. It had lists of 100 great books by many well-known people and a master list of the 100 books most mentioned in these lists ordered by the most mentions to those books with a lesser amount of votes, but still in some lists. I made it my goad to read all 100 books on the master list while I was in high school. I looked for another copy of the book for many years, and gave up. But just tonight, I think I found a used copy on Amazon. I have ordered it, and will report.
I did read all the books, and became an especial fan of novels translated from Russian. I didn't really like Of Human Bondage, being irritated with the protagonist, but I read it. And David Copperfield irritated me too, because of Davy's foolishness--I preferred other Dickens, especially the Pickwick Papers (don't ask!) but I stuck with it clear to the end. But I must admit, I really read only 99 of the books all the way through. I failed at The Meditations of Marcus Aurelius. I just couldn't stand it!
This has haunted me ever since. So I began my plan of redress.
The Meditations have been gracing my Kindle for some time now. When I promised a report yesterday, I was reading the introduction! Which went right along. Not thrilling, but interesting.
Now I am a very short way into the book. I could whine that
the Camera Club of Eagle meeting tonight cut into my reading time. . .
But the truth is that it is slow going.
I have found a great quote, though. Here it is:

"But it is now high time that you realized what kind of a universe
this is of which you form a part, and from wht governor of that universe
you exist as an emanation; and that your time here is strictly limited, and,
unless you make use of it to clear the fog from your mind,
the moment will be gone, as you are gone, and never be yours again."
(from the Oxford University Press version by Robin Hard and Christopher Gill.)

And it that doesn't get your thinkmeister going, I cannot think what will!
Grasp onto your plans for your emanation, think, and act! Or at least, be careful!