ONE OF the most important functions a writer has is to provide blurbs for other writers' books. The blurb business is one of the biggest in the country, and it is now estimated that 30,500,226 book blurbs are produced every year in the United States alone.

Everyone has seen book blurbs in advertisements such as, "Hym Golderweller has written another 'Godfather,'" or, "Not since 'War and Peace' has anyone caught the spirit of the women's liberation movement better than Sandra Bitter has in 'I Hate You, Marlon Brando.'"

There is a rule in the publishing business that no book can be printed unless the publisher receives 20 blurbs in its favor.

For the public unfamiliar with how book blurbs come about, I think I can be of service. When a book is about to be published, the author is asked by the publisher's publicity department to provide a list of friends, preferably well-known, who will say something nice about the work before publication.

The publicity department then sends out the galleys to people on the list. "Waldo Kransky has asked me to send you the galleys on his latest book, "The Fingers That Couldn't Walk Through the Yellow Pages.' Would you kindly send us your comments."

Now when I receive the galleys, I am faced with a dilemma. I don't have time to read Kransky's book, but obviously under the rules of the game, I have to provide a blurb. Otherwise, when I write a book Kransky won't give me a blurb.

About five books back I had neglected to give Kransky a blurb on his less than best seller, "The Sexual Myth of the Seat Belt," and I ran into him at a party. He was very miffed. I explained the reason I didn't give a blurb was that hsi publisher had sent me the typewritten manuscript, which was 900 pages, and I had dropped it on the floor. I could never get the pages back together in any kind of order.

Kransky found this unacceptable, and said he had taken his case to the Author's League, charging me with refusing to give a fellow author a book blurb, which is considered one of the most serious crimes a writer can commit.

A few days later the Author's League ruled in Kransky's favor, and I was forbidden to solitict book blurbs any member of the league for my text book. This was a cruel blow because without any blurbs, my publisher saw no reason to advertise my book.

I rifled through the galleys of "The Fingers That Couldn't Walk Through the Yellow Pages" and then sat down to write the blurb: "Kransky has done it again." I sent it off special delivery to his publisher.

Unfortunately, this was not the only book I had received that week. I had, in fact, gotten 14 galleys of books in the mail. Each required a different favorable quote, which wasn't easy since I had no intention of reading any of them.

I may not have made such a great effort, except that I have a new book coming out this fall, and I have been soliciting blurbs for myself. I knew the quality of the blurbs I would get was dependent on the quality of blurbs I wrote.

I spent all last week working on book blurbs for friends' books. It took me a day to come up with "Dynamite!" for a book on dieting, but only an hour to come up with "Eat your heart out, Norman Miller" for Maynard Bowditch's new biography titled, "I Never Knew Marilyn Monroe, Either."

There is some talk I may be nominated for a National Book Blurb Award this year. I hope so, because it would really kill Kransky.