It was Emily Dickinson who wrote, “a letter always seemed to me like immortality.”

After spending the past two decades uncovering boxes of handwritten diaries, letters composed on old typewriters and files of personal documents, professor and sociologist Adelaide Cromwell would have to agree.

Dr. Cromwell was raised in a red brick house in Washington, D.C. She lived with her father and mother and her three aunts. Her grandfather and other family members lived only blocks away. Yet, in her earliest memories, these people were little more than friendly faces and familiar names.

As she grew older, Ms. Cromwell learned little tidbits about them here and there. The aunt she was closest to, she learned, was the first black graduate of Smith College. Her father, who sent her to the best black high school in the city, was the first black practicing certified public accountant in Washington. Her grandfather, who died when Ms. Cromwell was just seven, was a lawyer, an educator and a newspaper publisher.

The rest of the story would come later. When her grandfather, John Wesley Cromwell, died, he left his belongings to Ms. Cromwell’s aunt, but his boxes sat in the basement untouched. When her aunt died in the 1970s, the boxes landed in Ms. Cromwell’s possession. She opened them to find decades and decades of records her grandfather had written, received and saved.

“I was fascinated,” Ms. Cromwell said this week from her Vineyard Haven home. “Unlike in many families, my aunts never sat me down and told me our family stories.” Ms. Cromwell spent the next 20 years reading, sorting and transcribing the material. When asked how many documents there were, she smiled a sly smile. “I have 80 letters that one aunt wrote to me while I was at Smith,” Ms. Cromwell said. “That should give you a sense.”

Ms. Cromwell is an independent woman who speaks her mind and thinks on her feet. To call her sassy would not be an understatement and, despite her 88 years, neither would it be out of the question to call her youthful. When recalling the doctoral thesis she wrote about the black elite in Boston back in 1952: “If I had a lot of money, I would have gone to more cities. It wasn’t like today where you can apply for these big fat grants.” When describing her first trip to Africa: “My trip was of the Mercedes Africa variety. I did not go into the bush.” When describing her new book, Unveiled Voices, Unvarnished Memories, which chronicles 280 years of her family history culled from the documents scrupulously saved by her grandfather: “It is not a book of hot gossip.”

Gossip the book may be short on, but the history within its pages is rich in detail and remarkable in story. It was in sorting through the documents that Ms. Cromwell first learned that her grandfather had been born into slavery. One day, while sorting through the documents, she pulled out a certificate which granted freedom to her great-grandmother, a Virginia slave. Her great-grandfather, Willis Hidges Cromwell, had earned the money while still a slave to buy his wife’s freedom, and, after becoming free, her great-grandmother worked to purchase the freedom of her husband and their children.

The family moved to Pennsylvania where their youngest son, Ms. Cromwell’s grandfather, began keeping a diary. “In reading his material, it is clear he expected someone to write about it,” Ms. Cromwell said. “But no one in my family was interested. And then I came along.”

Ms. Cromwell had spent her career asking questions and studying the cultures of black Americans and Africans. Now, she held the answers in her hands.

After graduating from Smith College with a degree in sociology, Ms. Cromwell went on to earn a master’s degree in the field from the University of Pennsylvania and a doctoral degree from Radcliffe College. While at Radcliffe, she wrote her thesis on the upper-class black community in Boston. “I came to find that the upper middle class took on the traits and characteristics of the city in which they lived,” she said. The thesis was later published as a book, The Other Brahmins. “My aunt thought I took too much sociology,” Ms. Cromwell recalled. “She said, ‘Why do you take so much sociology?’ Because I like it.”

Ms. Cromwell went on to become the first black instructor at Hunter College in New York and then at Smith. In 1951, she became a professor of sociology at Boston University and, in 1952, was instrumental in starting the African Studies program there. “Africa was stirring as a part of the world at this time,” she said. “People didn’t know much about Africa, about what was happening there. It was almost, in a sense, like the Middle East is now. Africa was awakening. There was a need to know.” The following year, she was appointed administrator and research associate of the program and, 16 years later, she helped found a graduate program in Afro-American studies at the university. She attributes her family with providing much of her drive. “I was raised with that mentality — if you were interested in black America, you had to be interested in Africa because that’s where it all started.” Ms. Cromwell later became director of the graduate program.

In the midst of all her work and study, Ms. Cromwell came to find the Vineyard. Her first visit was in 1945 and for the next couple of years, she returned, renting or staying with friends. She was finally driven to find a place to call her own 25 years ago, after an aunt she was staying with grew weary of the many callers who would stop by looking for Ms. Cromwell. She was at her Brookline home when her good friend and longtime Vineyard Haven resident Dorothy West called to tell her of a little property off Franklin street. “The Vineyard is a very important part of my life,” she said. “What I like is that you can live the kind of life you want to live here. There is a certain freedom. It’s close to Boston. I have some family who goes to Maine, but I wouldn’t want to go to Maine, the water’s too cold and it’s too far.”

Over the course of her career, Ms. Cromwell has authored five books and has traveled to Africa a number of times, but in the end, it was the tales of her own family which gave her an even richer understanding of black America. “It was like reading history,” she said of the letters, which include one from W.E.B DuBois and others which reference Booker T. Washington and Frederick Douglass. “But it was not emotional because it felt familiar already. Having done so much work in the black community, it was just another thing that happened to be mine.”

It was an understanding that would not have been possible without the letter. “People don’t write and what they do write, we throw away,” said Ms. Cromwell, who saves all of the letters she receives and writes all the ones she sends with a pencil on a yellow pad. She sat in a rocking chair, a halfway finished letter to her Smith classmates on the stool beside her. Ms. Cromwell is the secretary for her graduating class and it is her duty to personally correspond with the ladies, as she calls them. “If people do this and throw it away, we will have no records,” she said. “You’ve got to have these records.”