And yet we cannot tame it.

I understand the objection - clearly the Mississippi is not sentient, does not consciously choose what to do. It's a collection of matter that obeys the statistical laws of physics. Clearly the intuitive sense of the word 'agency' does not fit, at least to me. I think of agency as having the capacity for decision. But when I look at my dictionary, I see this definition first: "Faculty or state of acting or of exerting power; action, instrumentality".

We certainly cannot stop the Mississippi from flowing; is that not an exertion of power?