My friend Mike, who was kind enough to let me and my son use his house in California while he was away, is not going to like what I did there during the time he was gone: I listened to his answering machine. I did not mean to. I did not mean to snoop, but there were messages for me on his machine, and in order to listen to mine, I had to listen to his. This is how I learned the story of his life.

My first night in California, I returned to Mike's house and hit the button to rewind the tape. It whirred and whirred, and finally it stopped. On the tape it was July 4th, the date of the first message, although it was really the first week of September. A female voice, light and wispy, came out of the speaker: "Mike, this is Donna," she sort of sang. "It's July 4th, and I'm back in town. Give me a call-all."

I looked at my son and he at me. We do not have an answering machine at home. Instead, we have for years employed a housekeeper who takes the following sorts of messages: "A man called. A woman called." Now, though, we were not only getting messages, but the messages were in the voices of the people who called. It was as if we were listening in or tapping the phone.

I smiled at my son and he at me. The tape continued, and the messages came, one after another. Mike's summer rolled by -- the sexy voices of certain women, the all-business voices of men. A new Mike was revealed to me. The friend who never mentioned women to me was revealed on the tape to be something of a ladies' man. Women were calling him, and from the sound of their voices and what they said, it was not business they wanted to discuss.

After a while, I got to recognize some names. One woman in particular sounded wonderful on the phone. But it was clear that Mike was not returning her messages. I wondered why. She never got plaintive and never complained. Each message was cheery, almost brave: "Mike, it's me again. You haven't called." And then she would give the date and the time of her call.

I noticed a sex-linked pattern to the messages. Women were not intimidated by the machine. They were at ease with the contraption, while men seemed to freeze. The men were brief, sometimes curt and always business-like: "Mike, this is Joe. The meeting went fine. I just thought I'd let you know . . ." Then, almost always, there would be a long pause and then, like an afterthought, a blurted "Goodbye." As women already know, men do not know how to say goodbye. As men already know, women are adept on the phone.

I continued to listen to Mike's summer. I got to know some of the people that Mike was ducking and, from the sound of their voices, the women he seemed to like. Business propositions were suggested, floated and then came to earth with a thud: "Mike, this is Joe. The meeting didn't go well."

I admit there was a kind of voyeuristic thrill in listening to someone else's messages. It was like reading a diary or personal letters, although nowhere near as complete. The record left by the messages was fragmentary, but it was a record. In effect, my feeling of immense satisfaction at discovering a part of Mike I had not known (and never would have asked him about) was similar to the one people get when they read the diary or the letters of a famous person. Letters are often collected and published, but even if they are not, even if they remain archival material for scholars, they provide an insight into the thinking of the person and his or her times.

The answering machine pleased the historian-journalist in me. Here was a record. Here was a device that might fill the huge historical gap left by the demise of the letter. Letters have been replaced by the telephone, and a phone chat leaves no record. Someday soon, the last collection of letters will be published. Aside from those having to do with my columns, I don't think I get two personal letters a year -- and I write about as many. A collection of my letters (don't worry -- none is planned) would have to include those addressed to "resident" and "postal patron."

But look, for instance, at what we know about Franklin Roosevelt and Winston Churchill from their amazing, and often quite candid, exchange of letters. Harry Truman wrote about 1,200 letters to his wife, Bess, and while for all we know they may have bored her, they certainly have fascinated historians. From one of them, we learn that early on Truman thought Gen. Douglas MacArthur was an egomaniac. "Mr. Prima Donna, Brass Hat Five Star MacArthur," Truman called him in a letter to Bess. It just might be that Ronald Reagan's chats with Nancy are just as pithy and just as revealing, but there is no record of them. Reagan's biographer, Edmund Morris, in some ways has a harder time with his new subject than he had with his last, Theodore Roosevelt: T.R. was a compulsive letter writer.

Of course, messages on an answering machine are not the equivalent of letters. But they are better than nothing. They reveal facts of a person's life that otherwise might not be known. It is sheer folly to suggest or hope that important people will save their answering-machine tapes and turn them over to university libraries or biographers, but it is also too much to expect people like me, when given the opportunity, not to listen to them. The true historian, after all, has the soul of a snoop. ::