Do you keep a journal? How about old correspondence? Biographers will tell you that diaries and letters provide some of the greatest insights into their subject matters and also do good things for their authors. Yet in my dozens of interviews with successful people, only a few kept such personal histories—although many more wished they did.

In his biography of John Adams, the historian David McCullough draws from more than a thousand private letters between Adams and his wife, Abigail, as well as from their diaries. You gain a sense that their letters were not merely a record of their lives but of life itself. Abigail admitted that she could sometimes say things in writing more easily than in person. She got more opportunity than she wished to write her "Dearest Friend," as she affectionately addressed her husband, given their many years of separation when Adams was posted in Europe.

Separation also kindled the poignant letters that Suor Maria Celeste wrote to her father, Galileo, from her walled convent outside Florence in the 17^th century. In Galileo’s Daughter, the author Dava Sobel uses these letters to draw rich portraits of Galileo and his remarkable daughter. With her many privations and concerns for her father’s health and safety, how consoling Maria Celeste’s pen must have been for her.

Diaries, the ultimate in personal writing, can sometimes lead to writing that is the most widely read of all. Such was the case for Anne Morrow Lindbergh in the 1950s.

Taking a break from her difficult marriage to Charles Lindbergh and from her hectic family obligations, this dedicated diarist took some days for herself in a remote cottage on Florida’s Gulf Coast. There her reflections, initially written only for herself, eventually came to print in 1955 in a short book titled Gift from the Sea. It became one of the bestselling books of the century, striking a responsive chord with American women on the eve of the feminist movements of the 1960s.

While Anne Lindbergh was reflecting near a warm sea, an ambitious young reporter was covering the Cold War from inside Khrushchev’s Soviet Union, for the new medium of television. With his serious reporting on NBC and ubiquitous bow tie, Irving R. Levine became a television icon to a generation of Americans.

Irving has kept a diary and personal correspondence dating back to the 1940s. He recently re-read some old letters, finding things he had totally forgotten until he relived them half a century later.

"I have a letter describing my trip over to Europe the first time, on the Queen Elizabeth, and striking up an acquaintance with an Eva Pawlik, who was an Olympic skater, and then having dinner with her in Paris. I had forgotten that," he said in a recent interview.

This former newsman is a fast typist, and these days he writes his diary on the computer before printing it out. His diary also serves a metaphysical purpose. "It means that each day is something more. At least you’ve done something to make it stay by putting something down. I like grabbing the day in some form."

"I tell people to keep a five-year journal, and nobody values it until they do."
–Darlene Kostrub

Darlene Kostrub, the executive director of the Palm Beach County (Florida) Literacy Coalition, keeps several journals, each by hand. They are an important part of what keeps her centered in her busy professional and family life. She keeps a regular diary (usually starting a new one each year), a gratitude journal for occasional lists of what she is thankful for, and a book of days, sometimes called a five-year journal. This last kind of journal devotes just a few lines for each day, and each page holds entries for that same day for five years.

Of her book of days, Darlene explains: "I only put something there if it’s significant—when somebody dies, is married, if my kids broke up with somebody, or where we spend our family birthdays or the Fourth of July. I can tell you where we were and what we did."

Each year, on her close friend’s birthday, the two of them go out to celebrate. This year Darlene told her friend what they had done for each of the last five birthdays, "She couldn’t believe it. She was really impressed; it was gone from her mind," Darlene says. "I tell people to keep this kind of journal, and nobody values it until they do."

It’s not too late to start your own journal. No matter how little you write, or how irregularly, it can yield rewards in the coming years that will be worth far more to you than the minutes you invest in it today.

They say a friend is a gift you give yourself. So is a journal.

For my own part, I keep a sporadic journal on my computer, opening a new file for each month. Some months I have just a day or two when I’ve made an entry. Other months have pages and pages of writing. As a fast typist, and a slow hand writer, I prefer the keyboard. I also like the portability of a laptop, since I often find the time to write only when I’m on an airplane or in a hotel room by myself. A computer is convenient for moving words in and out of a journal. Sometimes I’ll be typing an entry when I realize my writing should really be a letter to someone, so I’ll copy the text out to a letter document. Other times, I’ll copy and paste in a letter or an email of significance, like the one I received from an old friend from high school. So my journal is an electronic scrapbook.

I print it out every few months and keep the pages in three-ring notebooks, having little faith in the future of digital storage. I’m comforted by the thought that I can go back and read my journal years from now. In my busy life today I don’t often leaf back, but when I do it’s like dipping a ladle in clear, cool water and taking a quenching drink. I savor again the ephemera of life that otherwise would drift away. They say a friend is a gift you give yourself. So is a journal.

Ten years later, I can still feel my pajama-clad boy do his flying leap into my arms from his changing table and hear the glee in his voice and kiss his chubby cheek again. Ahhh...if that’s not preserving important history, what is?