Common Sense
Sold 100,000 copies in three months in a country of two million. Paine's plain-spoken argument for American independence (that monarchy is absurd and hereditary rule is an insult to reason) transformed colonists' grievances into revolutionary ideology. The most influential pamphlet ever written.
The most common verdict is generational: readers meeting it as a school assignment shrug that “this book is literally just about common sense,” missing that it reads that way today precisely because this side won. The biblical section refuting the Hebrew scriptures on kingship is “mostly religious nonsense” to readers without the period's religious-political context, and it reads as tactically deployed since Paine was privately a deist who later attacked organised religion outright. Standalone editions pad well under fifty pages of actual Paine with introductions and companion pieces. And the archaic capitalisation trips readers with no practice in period prose.
The case for it and the rest of the canon open with Pro.
