Read the following passage from "Resistance to Civil Government" by Henry David Thoreau:

I have paid no poll-tax for six years. I was put into a jail once on this account, for one night; and, as I stood considering the walls of solid stone, two or three feet thick the door of wood and iron, a foot thick, and the iron grating which strained the light, I could not help being struck with the foolishness of that institution which treated me as if I were mere flesh and blood, and bones to be locked up.

How does Thoreau use ethos in the passage?