A few months after Francis Poulenc died in 1963, composer-auther Ned Rorem wrote in a memoir that Poulenc had, in his villa in Noizay, written "the greatest vocal music of this century."

Fifteen years have passed since that time. Now a new book by Poulenc's artistic colleague and close friend, the great French baritone, Perre Bernac, has appeared. It places the greates of this "greatest vocal music," the songs, under a clear and revealing spotlight that serves only to enhance Rorem's judgment. Bernac calls his book, "Francis Poulenc, the Man and His Songs."

Published by Norton, it speaks in detail of the 137 peoms and music that are the legacy of Poulenc songs. Since two-thirds of these were written specifically for Bernac to sing in concerts that he and Poulenc, as [WORD ILLEGIBLE] , gave in a period of over a quarter of a centruy, no one has a better personal, or a stronger artistic right to discuss them than the author.

It will be 30 years next November that Poulenc and Bernac gave their first concert in this country. That memorable event took place in this city, at Dumbarton Oaks, on Nov. 4, 1948. Those who were fortunate enough to be there that night heard Schubert songs sung in an unforgettable manner by a man who says of his own voice, "Why was I so irresistibly drawn toward singing? It was not because I had a superb and powerful voice, for this, alas, was not so."

Yet with that voice, which could easily sound ugly, Bernac sang some of the greatest songs of Schubert with an impact that was as intensely musical as it was compellingly dramatic. As he finished "Der Doppelgaenger," the effect was shattering. All that Bernac did was intensified by the faultless power of Poulenc's playing at the piano. For the composer, like his friend, Benjamin Britten, was not only a master composer for the voice, but a peerless pianist for singers.

What was totally new to most of the audience that evening at Dumbarton Oaks, a date that preceded by several days the public U.S. debut of these two great artists in New York City, was the music of Poulenc the composer. His cycle, "Tel jour telle nuit," to poems by Paul Eluard, left audiences in Washington, New York and Boston, in the composer's own words, "shouting, unbelievable," and the performers themselves, "flabbergasted" at the response.

These nine songs have been compared by the French author-critic, Roland Manuel, to the Schubert cycle, "Die Winterreise," and Schumann's "Dichterliebe." It is a verdict with which it is not at all difficult to agree.

Yet there are other songs by Poulenc that stand on the very same high pinnacles, not only in the minds of Poulenc admirers, but in the composer's own view as well. For example, of his setting of another Eluard poem, "Tu vois le feu du soir," Poulenc said, "I wonder if in the 'desert island' game this might not be the one I would choose from my songs to take with me." And it was yet another, to a poem by Apollinaire, "Montparnasse," that Poulenc recalled this way: "It took me four years to write 'Montparnasse.' I do not regret the time I spent on it for it is probably one of my best songs. Let us imagine," he added, "this Montparnasse suddenly discovered by picasso, Braque, Modigliani, Apollinaire. The more I reread Apollinaire, the more I am struck by the poetic role that Paris plays in his work."

It was, essentially, the poetry of these two men, "the poetry of our own time," as Poulenc called it, that inspired his greatest songs. It was those songs that he once said, "If on my tomb were inscribed: Here lies Francis Poulenc, the musician of Apollinaire and Eluard, I would consider this to be my finest title to fame."

It was, however, from neither of these poets that Poulence took the lines that formed the encore he and Bernac gave at that farr-off Dumbarton Oaks concert. When the audience refused to stop applauding, the two great musicians returned once more to the stage. Very quietly, Bernac said, "'C' de Poulenc." There then unfolded that simple, one-note-at-a-time introduction to the incomparable song Poulenc wrote in October of 1942, during the German occupation of France. With poetry by Louis Aragon, the song was published secretly.

"C" speaks of the terrible days in May 1940, when huge numbers of the French population were fleeing to escape the German invasion. Aragon himself, having crossed the Loire River over the historic bridges of Ce near Angers, wrote a tour de force of 18 lines, each of which ends with the sound of "ce." The resulting song strikes with the unexpected force of a hammer wrapped in black velvet.

Current record catalogs carry very few listings of Poulenc songs, and none of his great cycles, But his entire output of songs is now in the process of being recorded by the most sensitive artists available. It is, incidentally, true that today, though the world is not overcrowded with great Lieder singers, it has even fewer great singers of French art songs.

In a way it is strange that singers do not triumph in the songs of Poulenc. They are, first of all, always, and without exception, "vocal." That means they lie well for the voice, very few calling for either very high or very low notes. They are always rhythmically straightforward, a fact that some supercilious critics use in charging their composer with either superficiality or lack of musical sophistication. Finally, the songs always set the text in a way that places it clearly before the listener, even though that text may be one of the more obscure poems of Eluard.

What, then, makes Poulenc's songs so difficult to realize adequately? The answer lies not only in the elusive character of some of the poems - though others are remarkably clear and direct - but also in the subtleties of inflection in word and note that is essential for their finest projection. No songs by any composer are more explicitly guided by interpretive markings. Nor are any more grateful for the voice. They call for open, unabashed heart, and a universe of nuance, immculately conveyed in exquisite French enunciation and faultless musical style. That's all.

For further directions, and an illuminating guide to the heartbeat of a composer whose music I would not part with, read Bernac on Poulenc and his songs.Then besiege record shops for any discs of the songs made by Bernac and Gerard Souzay. (There is still available a two-disc Odyssey set by Poulenc and Bernac that is worth any price; it includes songs by a variety of composers including Poulenc.)

And do not overlook the Denise Duval recordings of the three operas: "Less mamelles de Tiresias," "Les dialogues des Carmelites," and "La voix humaine." Poulenc invariably referred to Duval as his "diven." In all this music there is a world of a special beauty that is unique. And a part of its greatness lies in the directness with which it speaks to the heart.