Nearly all men can stand adversity, but if you want to test a man's character, give him power.

This quote means that we can tell what kind of person someone is by observing how they behave when they have a lot of power. Most people are able to stay strong and handle hard times, but it is much more difficult to remain honest, responsible and fair when you have a lot of power. People might be tempted to use that power to take advantage of those who are weaker than them, so the quote suggests that we can learn more about someone’s real character when they have a lot of power.