“It's those that fight hardest for freedom who are never free.”

As quoted in Portrait — Adlai E. Stevenson : Politician, Diplomat, Friend (1965) by Alden Whitman

Time to Go Home, Yell Fire! (2006)

Source: What America Means to Me (1943), Ch. 4

Zebulon
Song lyrics, All Days Are Nights: Songs for Lulu (2010)

Context: For many South Koreans today, the Korean War is little more than a tragedy of the past or a tale in abstraction. For others, it is a trauma best forgotten. But on Memorial Day, the South Koreans, as a nation, must not forget the suffering and sacrifice in their national historical experience. The lessons of the most traumatic past must be learned and continually relearned, not only to prevent such a tragedy from repeating itself, but also to honor, as one nation, those who made our freedom possible, and to remember that freedom is certainly never free.

A Poet's Advice (1958)
Context: Almost anybody can learn to think or believe or know, but not a single human being can be taught to feel …
the moment you feel, you're nobody-but-yourself.
To be nobody-but-yourself — in a world which is doing its best, night and day, to make you everybody else — means to fight the hardest battle which any human being can fight; and never stop fighting.

"In Praise of the Fighters" (song)
Variant translation: There are men who struggle for a day and they are good.
There are men who struggle for a year and they are better.
There are men who struggle many years, and they are better still.
But there are those who struggle all their lives:
These are the indispensable ones.
As quoted in Democracy Unbound : Progressive Challenges to the Two Party System (1997) by David Reynolds; also quoted by Cuban musician and poet Silvio Rodríguez before his song "Sueño con serpientes".
Also quoted by Eduardo Galeano (Uruguayan writer) to describe Nestor Kirchner as he received the notice of his death.
The Mother (1930)