" A prisoner named Denis Martinez, for example, explained what getting an education and learning to read deeply into subjects gave him in terms of perspective: “It’s given me a new set of glasses. Before I wasn’t able to see the things I see now. I was a nineteen-year old knucklehead going around and thinking I knew it all. The more I learned the more I could sense how wrong I was and how many things I didn’t know.” Inspired by his reading of René Descartes, Martinez reflected, “There are two ways to be in prison—physically and/or mentally. Being in prison mentally is to live in ignorance, closed-mindedness, and pessimism. You can confine me for as long as you want, but my mind will always be free.” The title of a painting this prisoner made is revealing: Cogito Ergo Sum Liber—I Think Therefore I Am Free. (Now, there’s a bumper sticker/T-shirt slogan for the modern Enlightenment thinker.) "

― Michael Shermer , The Moral Arc: How Science and Reason Lead Humanity toward Truth, Justice, and Freedom