4 ideas
The word 'free' in free software refers to liberty — the right to run, study, modify, and redistribute code — not to zero price. This distinction reframes software not as a product to be sold but as knowledge that users have a moral right to control.
Copyleft uses copyright law against itself: a license grants anyone the right to copy and modify a work only on the condition that all derivatives carry the same freedoms forward. This makes openness viral and irreversible, since no one can take a shared work private without violating the terms that gave them access.
Stallman was denied the source code to a jammed laboratory printer because the manufacturer had bound its programmer with a nondisclosure agreement. This single act of being locked out of code he wanted to improve crystallized his conviction that proprietary restrictions are a betrayal of the cooperative ethic among programmers.
Withholding software source code is framed not as a neutral business choice but as an antisocial act that forbids people from helping their neighbors. The book asserts that the natural condition of useful knowledge is to be shared, and artificial restrictions on copying inflict real harm on a community.