I would also extend this remark to include free in addition to rich. “A man is free in proportion…” [Note: God would not apply to the quoted sentence as He is a person and not a thing. The quote could be re-read or completed as “You are free in proportion to how much you can afford to let things alone, and let God be before yourself.”]
Unless you can’t tell, I’ve on a Thoreau quoting kick as of late. So sue me. He is about as endlessly interesting and quotable as a man can get.