A crime persevered in a thousand centuries ceases to be a crime, and becomes a virtue. This is the law of custom, and custom supersedes all other forms of law.
— Mark Twain

Take the ideas of the masses (scattered and unsystematic ideas) and concentrate them (through study turn them into concentrated and systematic ideas), then go to the masses and propagate and explain these ideas until the masses embrace them as their own, hold fast to them and translate them into action, and test the correctness of these ideas in such action. Then once again concentrate ideas from the masses and once again go to the masses so that the ideas are persevered in and carried through. And so on, over and over again in an endless spiral, with the ideas becoming more correct, more vital and richer each time. Such is the Marxist theory of knowledge.
Mao Zedong persevered quote

People who have attained things worth having in this world have worked while others have idled, have persevered while others gave up in despair, and have practiced early in life the valuable habits of self-denial, industry, and singleness of purpose. As a result, they enjoy in later life the success often erroneously attributed to good luck.
— Grenville Kleiser

We've persevered because of a belief we share with the Iraqi people - a belief that out of the ashes of war, a new beginning could be born in this cradle of civilization. Through this remarkable chapter in the history of the United States and Iraq, we have met our responsibility. Now, it's time to turn the page.
— Barack Obama

I once thought that I was the only man that persevered to be the friend of the white man, but since they have come and cleaned out our lodges, horses, and everything else, it is hard for to believe the white man any more.
— Black Kettle