I have a partial explanation, and an imperfect (but good enough) decryption method.
Building on the excellent work by GentlePurpleRain, I noticed a pattern, which is much more apparent if we apply a small modification to his setup.
First of all, arrange the 40 symbols by columns instead, like this:
With this setup, the text looks like this:
As already established, + signs are spaces, and
| are periods. Now, look at
OAPPHAIAJP, which is the word that GentlePurpleRain already identified with
If you look at the alphabet table, you will notice that the encryption is a simple shift to the right.
With this hindsight, I tried to decrypt the first sentence, and I managed to get this:
Which, considering the reversed words, becomes obviously
That which is not owned cannot be held ransom for that which is.
Only problem is,
I had to try different shift values for each word, and I didn't find any particular rule. In case anyone is wondering, for that line the shift where: -3, -4, -1, -2, -4, -5, -1, -3, -5, -2 (negative means to the left).
I'll try and come up with a more precise rule.
As pointed out by f'' in the comments, the shift values are defined by the word's length (minus one, depending how you count).
I also have the full text:
That which is not owned cannot be held ransom for that which is. Distribution will never gain power over creation for the value of a product is inversely related to its availability. One offers cold settlement and another his warm gift.