WE ALL KNOW that first impressions are important. We're taught this at our mother's knee. So it should come as no surprise that first impressions of books, which are also called first printings or first editions, are also important and have been pursued by collectors for centuries.

A first meeting understandably contributes a lot to one's perception of a person; but the importance of a first printing may not seem as clear cut. Ah, but rationalization is a wonderful human attribute, for it furnishes a basis for what we have already decided we want to do. Whether by rationalization, logic or simply sentiment, certain of us become so enamored of books we treasure them as objects and only first editions will do.

A first edition is the first printing (first impression) of a book. It is true a first edition may have one or more printings and that a second edition will normally be issued only if there are actual changes, usually major, in the text. But as far as a collector is concerned, a first printing is the only true first edition.

The first thing to check when looking at a particular book is whether or not the dates on the title page and copyright page match. If the date on the title page is later than the date on the copyright page there is a good chance the book is a later printing. If there is no date on the title page there is a possibility the book is a reprint. There are certain publishers that normally do nothing but reprint books originally published by others. The best known are Grosset & Dunlap, A.L. Burt, Blakiston, Hurst, Modern Library, Sun Dial, Triangle and World's Tower Books. Any book published by these companies is a reprint in almost all cases.

There have been over 800 book clubs in the United States during this century. Many of these, I assume, sent their members regular trade editions, which might well be first editions. Other clubs printed their own editions. Normally there is no problem in identifying these: Usually the dust wrapper will state that it is a book club edition and no price will be marked. These are not first editions.

Since the late 1940s Book-of-the-Month Club books often look exactly like the publisher's editions (and frequently state "first edition/printing"). However, these can be identified as book club publications even without the dust jacket since they usually contain a small mark on the lower right corner of the rear cover. (Prior to 1948/49 it is difficult to differentiate the club's edition from the true first edition.) In earlier books that mark can be a small black circle, in more recent years merely a circular or square depression (blind stamp). Book-of-the-Month Club editions are not first editions even if they state "first edition." The Literary Guild book club editions also state "first edition," in many cases because the club printed from the original publisher's plates. But these books are also easy to identify since the spine and title page state "Literary Guild." Literary Guild editions are not first editions.

Many book club editions can also be identified as such by their paper and binding; these are often of poorer quality than that of the normal publisher's edition.

So if you've picked up a book at a garage sale and determined it is neither a reprint nor a book club edition, you should next check to see if the copyright page states that the particular book is a later printing; if it doesn't, then the book just might be a first edition.

How can you be sure? First editions are identified by the publishers, and there is unfortunately still no industry-wide system. Many publishers have changed their methods over the years, and a few have been so inconsistent that one has to resort to individual author bibliographies to be certain one has a true first.

With some exceptions, first editions are indicated in three ways.

1) A publisher will leave the copyright page (the verso of the title page) devoid of any information except copyright information. Second and subsequent printings will then either state the actual printing or list the complete printing history.

Publishers that have followed this method include Boni & Liveright, Jonathan Cape & Harrison Smith, Covici-Friede, Coward-McCann, John Day, Dial Press, Dodd Mead, Harcourt Brace (through 1930), Henry Holt, Alfred Knopf (through 1933/34), J.P. Lippincott, William Morrow, G.P. Putnam, Simon and Schuster (through the 1950s), and Vanguard.

(2) A publisher will state the printing beginning with the first printing. Publishers following this method include Atheneum, the Bodley Head, Jonathan Cape, Delacorte Press, Faber & Faber, Farrar Straus, Hamish Hamilton, Alfred Knopf (since 1933/34), New American Library, Random House (but also see below), Simon and Schuster (since the 1950s), and Viking Press ("First published by . . . in 19--" or "Published by . . . in 19--").

3) In addition to or instead of the foregoing methods -- and in an attempt to end the confusion -- around 1970 many publishers agreed to "standardize" the method of indicating firsts by using a series of numbers or letters on the copyright page to identify printings. But even here matters can be confusing. From the information available all publishers using this method (except two) start the series with a "1" or an "A," so a first printing would state "1 2 3 4 5 6 . . . " (in some cases, 1 3 5 7 9 8 6 4 2) or "A B C D E F . . ." In addition, many of the publishers also state "first edition" or "first printing" on the copyright page. For the second printing the publisher will delete the words "first edition" or "first printing" and the initial number (1) or letter (A). Then the series would begin with (or include) a "2" or "B," meaning that the book is a second printing.

I have noticed a few titles where the publisher deleted the number or letter but forgot to take off the "first edition" statement; consequently, you will sometimes find books stating "first edition" and the series "3 4 5 6 . . ." In this case, rely on the numbers: This would be a third printing.

The two exceptions (mentioned above) are Random House, which states "first printing" "2 3 4 . . . ", and Harcourt Brace which states "first edition" "B C D . . . " These publishers delete the words on the second printings. (Although recently, to add further confusion, I have noted that Harcourt has started including an "A" on their books.)

At present, most of the publishers use the number series or have reverted to their former methods. As you can see, the "standardization" effort has been less than a complete success. ALTHOUGH MOST publishers use or have used the three above systems to indicate first printings, in the past a few houses preferred even more idiosyncratic methods.

Appleton-Century used a numerical identification "(1)", "(2)", etc. at the foot of the last page of the book; Houghton Mifflin always placed the year of publication on the title page of the first printings and dropped the date on later printings (with no other changes on the title or copyright page); Scribner's placed an "A" on the copyright page of first printings since about 1930 (later they used a series of letters and numbers beginning with an "A"); Doubleday (in all forms) stated "first edition" on the copyright page of the first printing and dropped the statement on later printings (so that later printings resemble other publishers' first editions); and Doran, Farrar (in various guises) and Rinehart placed their initials or house designs on the copyright page of the first printing and dropped them on later printings, again causing confusion. ::

Allen Ahearn is the author of the standard reference, "The Book of First Books," and of the Authors Price Guides.