And there are many factors fuelling it, such as economic hardship and deep-seated feelings of social injustice.

BBC: Boston bombings: Was Dagestan the starting point?

But Einstein was outspoken against social injustice and violations of civil rights.

BBC: FBI campaign against Einstein revealed

In a populist address to Congress which was regularly interrupted by cheering and applause, Mr Rodriguez Saa pledged a "new republic" to "tackle social injustice and eliminate social conflict".

BBC: Argentina suspends debt payments

"The most positive legacy that Chavez has is that he put his finger on a legitimate grievance that many Venezuelans have: social injustice, " said Michael Shifter, president of the Inter-American Dialogue, a research and policy center in Washington.

CNN: Chavez leaves a revolutionary legacy

What was seen as the acute, structured corruption of the regime of Zine Al Abidine Bin Ali -- and the social injustice that resulted from it -- was a key impetus driving Tunisians into the streets in 2011.

CNN: Why Tunisia's leaders must resist urge for power grab

Nasar weaves people, places, politics, banking, social injustice, war, depression, recession, personal relations, personalities, sex, anti-Semitism, self-doubt, physical impairment, espionage, poverty, personal finance, self-delusion, self-interest, and much more in a book that educates as thoroughly and gracefully as it entertains.

FORBES: Sylvia Nasar's Grand Pursuit Is a Grand Gift

These four principles illustrate that the concept of sustainable development in the Earth Charter embraces the view that the problems of poverty, environmental degradation, ethnic and religious conflict, and social injustice are all interdependent, and that policies that address one problem can impact and improve other issues.

UNESCO: Understanding sustainable development