GettyImages-51417692
Nelson Mandela speaks to residents from the Phola park squatter camp on Sept. 5, 1990, in South Africa. Getty Images

Monday would be the 98th birthday of Rolihlahla "Nelson" Mandela, the former South African president known for helping negotiate the end of apartheid. It's also Mandela Day, a United Nations-recognized observance of the famous leader and his legacy. People are encouraged to follow Mandela's three favorite tenets: free yourself, free others, and serve every day.

"The question we must ask ourselves is what we are doing to make the world a better place; what are we doing to make every day a Mandela Day?" reads the website for the event.

Mandela, who died in 2013, was often eloquent when speaking about justice. Spread his message and make a difference by sharing a handful of his most famous quotes, collected from USA Today, Goodreads and the Guardian:

"Do not judge me by my successes, judge me by how many times I fell down and got back up again."

"Difficulties break some men but make others."

"Lead from the back — and let others believe they are in front."

"I always knew that deep down in every human heart, there is mercy and generosity."

"If I had my time over I would do the same again. So would any man who dares call himself a man."

"Part of being optimistic is keeping one’s head pointed toward the sun, one’s feet moving forward."

"I learned that courage was not the absence of fear, but the triumph over it. The brave man is not he who does not feel afraid, but he who conquers that fear."

"A good head and a good heart are always a formidable combination."

"It is said that no one truly knows a nation until one has been inside its jails. A nation should not be judged by how it treats its highest citizens, but its lowest ones."

"I have never regarded any man as my superior, either in my life outside or inside prison."

"Resentment is like drinking poison and then hoping it will kill your enemies."

"Everyone can rise above their circumstances and achieve success if they are dedicated to and passionate about what they do."

"Man's goodness is a flame that can be hidden but never extinguished."