Edward Abbey, Meet Seneca the Younger

Today, I was reading Seneca, and was struck by this sentence:

It is the mind that makes us rich; this goes with us into exile, and in the wildest wilderness, having found there all that the body needs for its own sustenance, it itself overflows in the enjoyment of its own goods. ("To Helvia")

I couldn't help wondering if Edward Abbey had ever studied the work of Seneca, or the Stoics in general. I certainly wouldn't be surprised. Despite the translation, Ed could have written this.