This book is a contradiction in terms. Theater lyrics are not written to be read but to be sung, and sung as parts of a larger structure: musical comedy, musical play, revue--"musical" will suffice. Furthermore, almost all of the lyrics in these pages were written not just to be sung but to be sung in particular musicals by individual characters in specific situations. A printed collection of them, bereft of their dramatic circumstances and the music which gives them life, is a dubious proposition. Lyrics, even poetic ones, are not poems. Poems are written to be read, silently or aloud, not sung. Some lyrics, awash with florid imagery, pre - sent themselves as poetry, but music only underscores (yes) the self-consciousness of the effort. In theatrical fact, it is usually the plainer and flatter lyric that soars poetically when infused with music.

Oscar Hammerstein II''s Oh, what a beautiful mornin'', Oh, what a beautiful day. I got a beautiful feelin'' Ev''rythin''s goin'' my way! is much more evocative than this couplet from his "All the Things You Are": You are the promised kiss of springtime That makes the lonely winter seem long. The first, buoyed by Richard Rodgers''s airy music, sounds as profoundly simple (especially if you ignore the dialect) as something by Robert Frost. The second sounds even more overripe than it is in print, given Jerome Kern''s setting, which merely by being music--and beautiful music, unfortunately--makes the extravagance of the words bathetic. Poetry is an art of concision, lyrics of expansion. Poems depend on packed images, on resonance and juxtaposition, on density. Every reader absorbs a poem at his own pace, inflecting it with his own rhythms, stresses and tone. The tempo is dictated less by what the poet intends than by the reader''s comprehension.

All of us, as we read poetry (prose, too), slow down, speed up, even stop to reread when overwhelmed by the extravagance of the images or confused by the grammatical eccentricities. The poet may guide us with punctuation and layout and seduce us with the subtle abutment of words and sounds, but it is we who supply the musical treatment. Poetry can be set to music gracefully, as Franz Schubert and a long line of others have proved, but the music benefits more from the poem which gives it structure than the poem does from the music, which often distorts not only the poet''s phrasing but also the language itself, clipping syllables short or extending them into nearunintelligibility. Music straitjackets a poem and prevents it from breathing on its own, whereas it liberates a lyric. Poetry doesn''t need music; lyrics do. Lyrics are not light verse, either. Light verse doesn''t demand music because it supplies its own. All those emphatic rhythms, ringing rhymes, repeated refrains: the poem sings as it''s being read.

Browning''s "The Pied Piper of Hamelin" percolates with unwritten music so strong that I would guess everybody reads it at the same trotting pace. In fact light verse, like "serious" poetry, is dimin ished by being set to music. Music either thuddingly underlines the dum-de-dum rhythms or willfully deforms them, trying to disguise the very singsong quality that gives the verse its character. This is why "The Pied Piper" has never been set well: take away the singsong and you destroy the poem, keep it in the music and you bore the listener mercilessly with rhythmic repetition. Music tends to hammer light verse into monotony or shatter its grace. It would seem easy to set Dorothy Parker''s famous "Comment" to music: Oh, life is a glorious cycle of song, A medley of extemporanea; And love is a thing that can never go wrong; And I am Marie of Roumania. The trouble is that she''s already done it. The jauntiness of the rhythm perfectly balances the wry self-pity of the words.

Music doesn''t understate, that''s not its job: its job is to emphasize and support the words or, as in opera, dominate them. Thus any accompaniment, whether light or lyrical, is likely either to turn Parker''s irony into a joke or to drown it in sentimentality. Light verse is complete unto itself. Lyrics by definition lack something; if they don''t, they''re probably not good lyrics. When it comes to theater songs, the composer is in charge. Performers can color a lyric with phrasing and rubato (rhythmic fluidity), but it''s the melody which dictates the lyric''s rhythms and pauses and inflections, the accompaniment which sets the pace and tone. These specific choices control our emotional response, just as a movie director''s camera controls it by restricting our point of view, forcing us to look at the details he wants us to notice. For the songwriter, it''s a matter of what phrase, what word, he wants us to focus on; for the director, what face, what gesture.

An actor singing "Oh, what a beautiful mornin'' " might want to emphasize "beautiful," but Rodgers forces him to emphasize "mornin'' " by setting the word on the strongest beat in the measure and the highest note in the melody. Song stylists-- club singers, recording artists, jazz vocalists and the like--often take liberties with lyric phrasings and tempos, but the music restricts their choices. This is not always a good thing: The unlucky lady who has to sing "Seven to midnight I hear drums" from Rodgers and Hart''s "Ten Cents a Dance" is forced to sing " hear drums" no matter how she squirms. The same holds true for anyone singing "It Never Entered My Mind" in the same team''s Higher and Higher ; she has to make "And order orange juice for one," sound natural. The songwriter sets the emphasis, for good or for ill. Another thing about music is that it isn''t explicit. Play a recording of Debussy''s La Mer for someone who hasn''t heard it and ask what it brings to mind. The reply will seldom be "The sea!," although in Music Appreciation courses that''s what is taught.

True enough, over the years certain orchestral sounds have come to be associated with specific emotions, especially in the movies (saxophones for sexiness, bassoons for clumsiness, flutes for happiness), just as certain instrumental themes resonate immediately from repeated exposure: Alfred Newman''s title music from Street Scene evokes New York, just as "Dixie" evokes the South and "La Marseillaise," France. Still, music is abstract and its function in song is to fulfill what it accompanies; poems are fulfilled all by themselves. Under spoken text, music is background, atmosphere and mood and nothing more. In song, music is an equal partner. Hammerstein, like all good lyricists, not only understood but counted on the power of music to glorify the understatement of his language, a collaborative surrender which poets who write for musical theater tend to underestimate or resist. Professional lyricists recognize music''s capacity not only to make a lyric vibrate, but also to smother it to death. If a lyric is too full of itself, as in "All the Things You Are," music can make it muddy or grandiose. The lyrics of Maxwell Anderson, Truman Capote, Anthony Burgess and Langston Hughes, to name some of the most prominent crossover poets, fall into this trap.

Their lyrics convey the aura of a royal visit: they announce the presence of the writer. When the stories deal with exotic times or cultures, as in Burgess''s lyrics for Cyrano and Capote''s for House of Flowers , the self- consciousness can be acceptable, but when the characters are supposed to be speaking in the vernacular, as in Hughes''s Street Scene and Anderson''s Lost in the Stars , the lyrics become faintly but persistently ludicrous. It''s the music that does them in. Poets tend to be poor lyricists because their verse has its own inner music and doesn''t make allowance for the real thing. The two great exceptions are DuBose Heyward''s lyrics in Porgy and Bess and Richard Wilbur''s in Candide . Their work bespeaks an understanding not only of how music operates with words, but of how words operate in drama. They know how to combine the density of poetry with the openness of lyrics and still not intrude their own selves into the characters. I hasten to add that intrusion is a problem for non- poet lyricists as well.

To cite a favorite example of my own, from West Side Story : "It''s alarming / How charming / I feel," sings Maria, a lower- class Puerto Rican girl who has been brought up on street argot and whose brother is a gang leader, but who suddenly sings the smoothly rhymed and coyly elegant phrases of a character from a Noël Coward operetta because the lyricist wants to show off his rhyming skills. In opera, density is less of a problem because text occupies a back seat. Usually, the lyrics matter minimally except when necessary to carry the plot forward, and most operas have very little plot to carry-- traditionally, the drama is supposed to be carried by the music. The lyrics by W. H. Auden and Chester Kallman for The Rake''s Progress read gracefully and sing unintelligibly, not only because Stravinsky distorts them but because they''re too packed for the listener to comprehend in the time allotted for hearing them. If poetry is the art of saying a lot in a little, lyric- writing is the art of finding the right balance between saying too much and not enough. Bad lyrics can be either so packed that they become impenetrable or so loose that they''re uninteresting.

Most lyrics written in my generation and the generations before me do not make for good reading. Nostalgists for what is popularly termed the Golden Age of Musicals (1925-1960), who appreciate how good many of the songs were and ign.