Joseph‌ ‌Ellis‌ ‌cites‌ ‌two‌ ‌reasons‌ ‌why‌ ‌he‌ ‌believes‌ ‌John‌ ‌Adams‌ ‌took‌ ‌the‌ ‌“fateful‌ ‌step,‌ ‌which‌ ‌led‌ ‌to‌ ‌a‌ ‌fourteen‌ ‌year‌ ‌exchange‌ ‌of‌ ‌158‌ ‌letters”‌ ‌between‌ ‌him‌ ‌and‌ ‌Jefferson

Ellis' first reason is that he believed Adams wished to directly “challenge the Jeffersonian version” of the American Revolution, to basically win the argument (223). The second reason is that Adams wished to be recorded appropriately for history.