What would be Nelson Mandela’s 97th birthday is Saturday, and the world will spend the weekend remembering the legendary leader. Mandela, who spent 27 years in prison and famously brokered the end of the apartheid in South Africa, served as the country's first black president from 1994 to 1999. From then until his death from a respiratory infection in 2013, he advocated for democracy and peace.

Today, people everywhere celebrate Mandela Day, which the United Nations General Assembly created in honor of the activist's birthday. Mandela Day's website encourages participants to abide by his three moral rules: free yourself, free others and serve every day. It's a chance to make the world a better place.

Throughout the course of his life, Mandela gave several memorable speeches. Read a few of his most inspirational quotes below, collected from GoodReads and Wikiquote:

1. “Live life as though nobody is watching, and express yourself as though everyone is listening.”

2. “Your playing small does not serve the world. Who are you not to be great?”

3. “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.”

4. “I am not an optimist, but a great believer of hope.”

RTR1KVPW Nelson Mandela raises his fist to the crowd in Port Elizabeth, April 1, 1990. Photo: Reuters

5. “It is not where you start but how high you aim that matters for success.”

6. “When the history of our times is written, will we be remembered as the generation that turned our backs in a moment of global crisis or will it be recorded that we did the right thing?”

7. “It is what we make out of what we have, not what we are given, that separates one person from another.”

8. “No one is born hating another person because of the color of his skin, or his background, or his religion. People must learn to hate, and if they can learn to hate, they can be taught to love, for love comes more naturally to the human heart than its opposite.”

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

RTR25T2Z Nelson Mandela appears in a previously taped video during the Mandela Day concert at Radio City Music Hall in New York on July 18, 2009. Photo: Reuters

10. “There is nothing like returning to a place that remains unchanged to find the ways in which you yourself have altered.”

11. “Courageous people do not fear forgiving, for the sake of peace.”

12. “When a man is denied the right to live the life he believes in, he has no choice but to become an outlaw.”

13. “I had no epiphany, no singular revelation, no moment of truth, but a steady accumulation of a thousand slights, a thousand indignities and a thousand unremembered moments produced in me an anger, a rebelliousness, a desire to fight the system that imprisoned my people. There was no particular day on which I said ‘Henceforth I will devote myself to the liberation of my people;’ instead, I simply found myself doing so, and could not do otherwise.”

RTXFGSC Nelson Mandela stares out of the window of the prison cell he occupied on Robben Island for much of his 27 year incarceration, on Feb. 11, 1994. Photo: Reuters

14. “The greatest glory in living lies not in never falling, but in rising every time we fall.”

15. “What counts in life is not the mere fact that we have lived. It is what difference we have made to the lives of others that will determine the significance of the life we lead.”

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

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