True leadership will not be measured by the ability to muzzle dissent, or to intimidate and harass political opponents at home. The people of the world want change. They will not long tolerate those who are on the wrong side of history.
In Iraq and Syria, American leadership - including our military power - is stopping ISIL's advance, instead of getting dragged into another ground war in the Middle East, we are leading a broad coalition, including Arab nations, to degrade and ultimately destroy this terrorist group.
Criticism may not be agreeable, but it is necessary. It fulfils the same function as pain in the human body. It calls attention to an unhealthy state of things.
Concern for man and his fate must always form the chief interest of all technical endeavors. Never forget this in the midst of your diagrams and equations.