Mary Moody Emerson (August 23, 1774 – May 1, 1863) was an American letter writer and diarist. She was known not only as her nephew Ralph Waldo Emerson's "earliest and best teacher", but also as a "spirited and original genius in her own right".[1] Ralph Waldo Emerson considered her presence in his life a “blessing which nothing else in education could supply”;[2] and her vast body of writing—her thousands of letters and journal entries spanning more than fifty years—"became one of Emerson's most important books".[3] Her surviving documents reveal the voice of a "woman who […] had something to say to her contemporaries and who can continue to speak to ours" about "the great truths that were the object of her life's pilgrimage".[4]