IN ANY attempt to understand Bob Dylan's works, one ought to consider his music, his lyrics and his singing style separately, since each of these three elements has different history in the development of his art. Their conjunction--in the various stages of each's evolution--is responsible for both the wide variety of Dylan's musical output, and its enduring unity.

Dylan's music has, essentially, always been rock and roll. In his early years he was forced to sing in the prevailing folk idiom of the times because there was no other way to break into big-time entertainment. Even then, however, most of his songs had a rock feel to them, a fact which was quickly appreciated by Manfred Mann in England and the Byrds in this country. Both groups had only to supply the standard rock accompaniment of drums, guitars, etc. to make enormously successful covers of early Dylan songs.

So Dylan's subsequent entry into rock, which so scandalized the folk fans at Newport, was the logical, and inevitable, outcome of a deep-seated movement in that direction. Nevertheless, it is clear that Dylan emerged considerably enriched from his experience in folk-music. In the first place, the free and bohemian atmosphere of the folk-world allowed, if it didn't encourage, Dylan to develop his own unorthodox singing style, in all the expressive glory of its distorted, flat phrasing.

Secondly, Dylan found that the hip, urban folk-music audience of the '60's hungered for, and savored, complicated and highly-strung lyrics. Dylan responded to this demand for "meaningful" lyrics with alacrity and in the process developed two extraordinarily powerful strains in his songwriting. One set of lyrics dealt with social ills; the songs in this group started out a fairly simple-minded protest songs and ended up as fierce expressionistic collages of the sights and sounds of modern America. The other set of lyrics was Dylan's special breed of love songs, at the same time supplicating and defiant, tender and cruel.

IN ANY CASE, when Dylan burst into full-fledged rock with Highway 61 Revisited (and in the sublime follow-up Blonde on Blonde) he fused rock-music with his legacy from folk-music: the eccentric tension-filled voice, and the sharp-edged songs whose writing he had come to master. This particular combination proved to be unrelentingly right, with the three elements of voice, words, and music interacting upon one another like rigorously synchronized interlocking wheels.

It is in this context and with these categories in mind that one could try to weight Nashville Skyline. Three years after Blonde on Blonde,Bob Dylan remains solidly in rock and roll. The new album, despite all the talk about country music, is definitely a rock album--though to be sure it is calm rock, gentle climaxes, active relaxed drumming, generally vibrant rhythm section, crisp guitar work, strumming organ and all. And clearly, this music is equal to Bob Dylan's best.

The rock on Nashville Skyline is not as tense and irascible as the music on Blonde on Blonde was. This is no accident. Bob Dylan's sense of fitting the music to the words and the general mood of an album has not deserted him. Since the lyrics are low-key and gentle the music is appropriately smooth rock and roll. In turn this configuration of words and music, I thing, determined Dylan's use of his voice on the album (which as everyone knows by now, is radically different from the grating, flaring voice we used to recognize as Dylan's.) I cannot imagine how Dyland could have conceivably sung this album's songs differently.

NEVERTHELESS I suspect the Nashville Skylineis not an album that anyone is going to treasure or play over and over again for years to come. It's not another Blonde on Blonde and in that sense it remains a disappointment. For the essential point about Bob Dylan's claim to artistic greatness is the quality of his rock-poetry. Words are overwhelmingly important in Dylan's creations.

On all his previous albums Dylan wrote with a brute, manic verbal agility, unerringly treading the fine line between preciousness and overstatement. Thing of "The pump don't work / cause the vandals took the han-dle" or "I've got the fever / Down in my pock-ets" of "And the jelly-faced women all sneeze."

And this uncanny poetic ability of Dylan's was put at the service of the songs of his two great themes, frustrating love and frustrating life, and sung in that unforgettable incandescent jarring voice. Which is why those songs to this day carry such an explosive charge.

Nashville Skyline, by contrast, has no tragedy and no drama. The poetry is damp and the songs essentially trivial. There really is not way of getting around it. Dylan seems too happy to be able to create masterpieces and one is glad only for his sake. There will be more records in the future, no doubt, but will they not be like Nashville Skyline, pleasant an perfect but low-level? And to think I almost didn't believe once the old saw that artists have to suffer or they're not artists.