But if survival calls for the bearing of arms, bear them, you must. As we all have. Keep in mind only this, that province of combat is not the end, it is simply the means. And the most essential part of the challenge is for you to find another means that does not come with the killing of your fellow-man.

Rod Serling (1924-1975) American screenwriter, playwright, television producer, narrator

Commencement Speech, Binghamton Central High School, Binghamton, New York (28 Jan 1968)
    (Source)

Sometimes paraphrased:

If survival calls for the bearing of arms, bear them you must. But the most important part of the challenge is for you to find another means that does not come with the killing of your fellow man.