Until recently, the practice of diary-keeping had nearly disappeared from modern life. "Nearly," because this rather cumbersome and old-fashinoned way of recording one's thoughts, plans, hopes and deeds was being kept alive only by political assassins, who are all faithful diary-keepers, going at it without even the expectation of grants from foundations interested in preserving thisart.

For others, it had been supplanted by more immediately satisfying methods of unloading the mind. If you tell your troubles to Dear Diary, it doesn't reply at the end with something comforting, such as "Gee, them's the breaks, I guess," or "Your hour is up."

Nevertheless, diary-keeping is making a comeback, precisely because it has been suggested as a new form of therapy. It is certainly quieter and cheaper than some of the more recently popular methods, and there's a lot to be said for giving a few of the more extravagantly emotional victims of the society pencils to close their mouths around.

Naturally, it is not being suggested just that you be issued a pencil and a spiral notebook. Diary-keeping as therapy involves workshops, casettes, systems and books. But it is catching on among those who have discovered that a diary does not look glassy-eyed after your innermost confessions and reply, "Yes, I know, but you already told me."

However, it is in its infancy as a therapy, and perhaps some of the pitfalls should be considered.

What happens when you begin to notice how fascinating your life really is? We are now at a cultural stage where we are not as interested in finding out about the unusual as we are in knowing about how a select number of people conduct the ordinary parts of their lives. One Cher having a baby is worth several axe murderesses. Suppose you notice how entrancingly usual your life is, and acquire ideas about film rights, television serialization and candid pictures of yourself relaxing at home in People magazine? You then have to start rewriting the entire book, in terms of the early life of someone who is later to be a celebrity. And that's going to kill it all off right there, because nobody likes to do rewrite.

Or suppose you decide that it is not dramatic enough, even in terms of the sort of domestic drama you have envisioned. For an honest diary, you have to start working on the life in order to jazz up the book. This is more work that in time could be better spent telling your troubles to a live listener.

Or suppose you record your life in a true and spell-binding manner, exactly in a style that will be absorbing to whoever sees it. There you are, with all your engaging peccadillos, your juicy secrets, your memorable impressions of why you did what you did.

You'd still have to consider that it would be admissible in court. And that's why people stopped keeping diaries in the first place, and why the practice of attending the divorce trials of interesting people has also pretty much died out.