<h2 class="eplus-1DN1Eh">Is moral courage stronger than physical force? A photograph of a nun pleading with police in Myanmar not to use violence against demonstrators reminds us of the power of peaceful protest.</h2>

"I was crying like a mad person," she said afterwards. "I was like a mother hen protecting the chicks... At that time I was not afraid."

Nu Tawng was undoubtedly taking her life in her hands. More than 60 people have been killed in demonstrations since Myanmar's military overthrew Aung San Suu Kyi's elected government on 1 February. The army that murdered civilians during the persecution of the Rohingya Muslims has shown little compunction about treating democracy protestors in the same way.

Tragically, Nu Tawng's action on Monday did not prevent bloodshed: two men were shot dead by police in the city, one of them in front of her eyes. But its long-term effect remains to be seen. The photograph of her has been widely shared on social media, making her an inspiring symbol of resistance to a savage regime.

It was also a potent reminder of other images of individual courage in the face of overwhelming odds. One was the photograph taken in June 1989 of a lone man blocking the path of tanks in Beijing, after the Chinese government violently suppressed pro-democracy demonstrations in Tiananmen Square.

Another was the "Flower Power" photo of a young protestor placing a carnation in the barrel of a soldier's rifle during an anti-Vietnam War march on the Pentagon in October 1967 - despite several other rifles being pointed at his chest.

More recently, the Black Lives Matter movement has produced some searing images of women standing up to the police. One shows a Baton Rouge resident, Ieshia Evans, clad in an elegant dress, standing calmly in the middle of the road as she is arrested by two policemen wearing full body armour.

The modern tradition of nonviolent protest owes much to Mahatma Gandhi, who promoted the idea of Satayagraha - a Sanskrit and Hindi word meaning "holding onto truth". He argued that the best way to resolve an evil situation was to behave in an exemplary manner and bring those who oppose you around to your way of thinking.

Gandhi first developed Satayagraha in response to a law in South Africa, where he lived, which discriminated against Asians. He then advocated it with great success in India, where tactics such as economic boycotts and hunger strikes were used to undermine British rule. It later became a strong influence on the American civil rights movement led by Martin Luther King.

<h2 class="eplus-VaM43O">We shall overcome</h2>

In ancient times, the importance of individuals standing up to tyranny was strongly emphasised. Sophocles' great play, Antigone, focuses on a young woman who risks her life by defying Creon, the ruler of Thebes.

Is moral courage stronger than physical force?

Some say, no. Nu Tawng was unable to stop innocent protestors from being killed. The man who defied the tanks in Beijing could not stop the Chinese government from suppressing the pro-democracy movement. Alexei Navalny's protests against corruption in Russia have failed to dislodge President Putin and simply resulted in jail sentences for him and his supporters.

Others point out that movements for change are always stronger if they have a particular figure to inspire them. The success of the independence movement in India can be attributed directly to Gandhi's vision and courage. In Czechoslovakia, the playwright Vaclav Havel was thrown into prison by the Communist regime, but his example emboldened others in their successful struggle for democracy.

Tiananmen Square - A huge open space in the middle of Beijing. It is known for a large-scale student protest that took place there in 1989 before being brutally crushed by China's communist rulers.

Mahatma Gandhi - An Indian political activist and lawyer (1869-1948), who emphasised passive resistance.

Sophocles - A 5th Century BC Athenian believed to have written 123 plays, seven of which survive.

Thebes - A city state in Ancient Greece. Confusingly, it shared its name with a city in Ancient Egypt.