„Radical groups in the 1960s developed a reputation for factionalism: organizations split because of disagreements on details of strategy, and then treated each other as enemies. Or at least, such is the image people have of them, whether or not it was true.
The relationship between the Free Software movement and the Open Source movement is just the opposite of that picture. We disagree on the basic principles, but agree more or less on the practical recommendations. So we can and do work together on many specific projects. 'We don't think of the Open Source movement as an enemy. The enemy is proprietary software.“
— Richard Stallman American software freedom activist, short story writer and computer programmer, founder of the GNU project 1953
1990s, Why "Free Software" is better than "Open Source" (1998)