Andrew, I am so glad to hear that you love Jeffers. Imagine how lucky is Simon (see G.A. forum) to have a tangible connection to Jeffers and his environment!
I'm not getting his distinction between "natural" and "noble sentiments" at the end. Aren't they both an aspect of the same thing?
Yes, I would say that they are. For Jeffers, nothing that human beings do or can do is "unnatural." As he says in his poem "Calm and Full the Ocean" "... even the P-38s and Flying Fortresses are as natural as horse-flies." But for Jeffers, "those holy or noble sentiments, the intricate ideas, / The love, lust, longing ..." are side-issues, secondary distractions from the main show - the "transhuman magnificence" of Nature. These are human "reasons" for being, but not THE reason: Beauty.
Jeffers is all for the religious immanence of the Divine, not for a human transcendence toward it, as if it were somehow "outside" the universe.
For anyone listening in on our present public private correspondence, here is a link to more on Jeffers.
http://members.aol.com/PHarri5642/jeffers.htm