•Why it earns a slot
Published in 1690 to justify England's Glorious Revolution, the Second Treatise supplied the foundational vocabulary of consent, natural rights, and limited government that directly shaped the American Declaration of Independence and modern constitutional theory.
Locke argues that legitimate government rests entirely on the consent of the governed, whose natural rights to life, liberty, and property pre-exist any political authority. He traces how people leave the state of nature to form civil society, what limits constrain the legislative and executive powers they create, and under what conditions those powers may be dissolved and replaced. The treatise concludes that when rulers betray the trust placed in them, the people retain the supreme right to resist and reconstitute their government.
This distillation is written from the freely available original, which is always the better read when you have the time: gutenberg.org.