Common Sense was a widely-read pamphlet published in 1775-6 that argued for American independence from British rule. The pamphlet's simple, down-to-earth tone made it widely-accessable to Americans in the colonies. In the pamphlet's four sections, Thomas Paine argues for 1. a balance between society and government that he thinks the British monarchy has violated, 2. that all men are created equal and monarchy was unjust, 3. that America should organize a continental congress to represent the people, and 4. that the colonies have the military power to defeat the British.
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The most popular website for book notes. SparkNotes was created by students for students, and their summaries are accessible and extremely well-written. Besides the usual plot overview, chapter summaries, and character analysis, SparkNotes differentiates itself with a section discussing themes, motifs, and symbols.