A weapon is a device for making your enemy change his mind.

I call upon the scientific community in our country, those who gave us nuclear weapons, to turn their great talents now to the cause of mankind and world peace, to give us the means of rendering those nuclear weapons impotent and obsolete.
About his proposed Strategic Defense Initiative, later to be known as 'Star Wars.')

In the arts of life main invents nothing; but in the arts of death he outdoes Nature herself, and produces by chemistry and machinery all the slaughter of plague, pestilence and famine. … There is nothing in Man's industrial machinery but his greed and sloth: his heart is in his weapons.

It occurred to me that if I could invent a machine - a gun - which could by its rapidity of fire, enable one man to do as much battle duty as a hundred, that it would, to a large extent supersede the necessity of large armies, and consequently, exposure to battle and disease [would] be greatly diminished.

Our scientific power has outrun our spiritual power. We have guided missiles and misguided men.
Commenting on the way the Vietnam War was being conducted by the U.S.

The fact that no limits exist to the destructiveness of this weapon [i.e. the atomic bomb] makes its very existence and the knowledge of its construction a danger to humanity as a whole. It is necessarily an evil thing considered in any light. For these reasons, we believe it important for the President of the United States to tell the American public and the world what we think is wrong on fundamental ethical principles to initiate the development of such a weapon.

The knife is the most permanent, the most immortal, the most ingenious of man's creations. The knife was a guillotine; the knife is a universal means of resolving all knots...

The pen is mightier than the sword … only if the sword is very small and the pen is very sharp.

The science of weapons and war has made us all one world and one human race with one common destiny.

The sole precoccupation of this learned society was the destruction of humanity for philanthropic reasons and the perfection of weapons as instruments of civilization.

The terror created by weaponry has never stopped men from employing them.