“If things do not change, there will be nothing left to change. Either power must pass to the people or everything will perish.”

Variant: All things change; nothing perishes.
Source: Metamorphoses

Rolling Stone interview (1968)
Context: Everything I've learned in life I've learned either by doing it or watching the changes other people go through. And when you're famous, you don't get to meet people — because they want you to like them when they present themselves to you, present the best sides of themselves, and you don't see the real people. Which is why I don't really go anywhere. And when I do, I put on my silly face and do what they expect me to do. Actually, I never do what they expect me to do. It's the only way I could go on doing what I have to do. I do whatever I… you know, I didn't even comb my hair today. I didn't know we were taking pictures but when I found out, it didn't change my mind any.

"Poem IX", in Complete Works St. Teresa of Avila (1963) edited by E. Allison Peers, Vol. 3, p. 288
Context: Let nothing disturb thee;
Let nothing dismay thee:
All things pass;
God never changes.
Patience attains
All that it strives for.
He who has God
Finds he lacks nothing:
God alone suffices.

Source: Red Glove

2013, Commencement Address at Ohio State University (May 2013)
Context: That’s precisely what the founders left us: the power to adapt to changing times. They left us the keys to a system of self-government – the tool to do big and important things together that we could not possibly do alone. To stretch railroads and electricity and a highway system across a sprawling continent. To educate our people with a system of public schools and land grant colleges, including Ohio State. To care for the sick and the vulnerable, and provide a basic level of protection from falling into abject poverty in the wealthiest nation on Earth. To conquer fascism and disease; to visit the Moon and Mars; to gradually secure our God-given rights for all our citizens, regardless of who they are, what they look like, or who they love. 
We, the people, chose to do these things together. Because we know this country cannot accomplish great things if we pursue nothing greater than our own individual ambition. 
Still, you’ll hear voices that incessantly warn of government as nothing more than some separate, sinister entity that’s the root of all our problems, even as they do their best to gum up the works; or that tyranny always lurks just around the corner.  You should reject these voices. Because what they suggest is that our brave, creative, unique experiment in self-rule is just a sham with which we can’t be trusted.
We have never been a people who place all our faith in government to solve our problems, nor do we want it to. But we don’t think the government is the source of all our problems, either. Because we understand that this democracy is ours.  As citizens, we understand that America is not about what can be done for us. It’s about what can be done by us, together, through the hard and frustrating but absolutely necessary work of self-government. 
The founders trusted us with this awesome authority. We should trust ourselves with it, too. Because when we don’t, when we turn away and get discouraged and abdicate that authority, we grant our silent consent to someone who’ll gladly claim it.