At once time Mr. Douglass was travelling in the state of Pennsylvania, and was forced, on account of his colour, to ride in the baggage-car, in spite of the fact that he had paid the same price for his passage that the other passengers had paid. When some of the white passengers went into the baggage-car to console Mr. Douglass, and one of them said to him: "I am sorry, Mr. Douglass, that you have been degraded in this manner," Mr. Douglass straightened himself up on the box upon which he was sitting and replied: "They cannot degrade Frederick Douglass. The soul that is within me no man can degrade. I am not the one that is being degraded on account of his treatment, but those who are inflicting it upon me."
p. 100, Up from Slavery, Booker T. Washington
[...] when I was being stripped and searched, I decided it was best to treat my captors like the weather. A storm can cause you problems, and sometimes those problems can be humiliating. But the storm itself doesn't humiliate you.
Once I understood this, I realized that nothing they did could humiliate me. I could only humiliate myself -- by doing something I might be ashamed of. During my first few days in Lefortovo I repeated this principle over and over until it was part of me: Nothing they do can humiliate me. I alone can humiliate myself. Once I had absorbed that idea, nothing -- not searches, not punishments, and, five years later, not even several attempts to force-feed me through the rectum during an extended hunger strike -- could deprive me of my self-respect.
p. 8, Fear no Evil. Natan Sharansky