First they came...
First they came for the communists, and I did not speak out—because I was not a communist;
Then they came for the socialists, and I did not speak out—because I was not a socialist;
Then they came for the trade unionists, and I did not speak out—because I was not a trade unionist;
Then they came for the Jews, and I did not speak out—because I was not a Jew;
Then they came for me—and there was no one left to speak out for me.
a popular poem attributed to Pastor Martin Niemöller (1892–1984)
more about it here: http://en.wikipedia.org/wiki/First_they_came...
It seems simple but it exactly describes where apathy would lead to...
The poem is from Nazi era's genocide. And it depicts well of the cause of Khmer Rouge era's genocide; leading Cambodia back to Year Zero in 1975.
While, sympathy (and empathy) is the foundation of humanity, apathy is the cause of failure in humanity. And it is why we must speak up for the powerless.