."Yes, I have read India's Heroes.
The particular line means that all people do not react the same when they are in danger.
Their psychology makes them act in different ways.
As we can take some real life incident:
The terrorist attack on the unsuspecting people of Mumbai on 26th November 2008 threw up several brave hearts.
People stood up to fight against the terrorist while some ran away seeing them saving their lives.
So, here is how they reacted, some stood bravely not thinking about their lives and wanting to save other people from the terrorist attack while there were people who thought just about them and ran only to save their lives.
Hope it helped.. :)