Which documen twritten mostly by thomas Jefferson explained the reasons why the colonies were breaking away from Britain?

The document you are referring to is the Declaration of Independence, primarily authored by Thomas Jefferson in 1776. It articulates the colonies' grievances against King George III and outlines the philosophical justification for their separation from British rule, emphasizing principles of individual rights and government by consent. This seminal text served as a foundational declaration of the colonies' pursuit of liberty and self-governance.