IT WAS part of Dvorak's genius that he could so steep himself in the folk idiom that his own tunes could pass for "the real thing." He explained that this had been his procedure in composing his final symphony, "From the New World," during his sojourn in our country, but numerous commentators nevertheless persisted in describing the themes in that work as having been derived from Indian songs and Negro sprituals.

Dvorak used the same technique earlier in composing his two sets of Slavonic Dances. These are not concert settings of folk tunes, as are Brahms' Hungarian Dances, but miniature tone poems, built entirely on original material, in which Dvorak celebrated nature and folklore in idealized dance forms.

The forms he used came not only from his own country but from such Slavic neighbors as Poland, Serbia and the Ukraine.

One might think the proprietary zeal the Czech Philharmonic Orchestra brings to performances of the Slavonic Dances is such that it hardly matters who happens to be on the podium. The great Prague orchestra undoubtedly does bring out a quality in this music that even the finest Czech conductors don't quite achieve with ensembles in Vienna, Cleveland, London or Munich, but the conductor also makes a difference.

The Czech Philharmonic recorded the completed Opp. 46 and 72 sets twice under the unforgettable Vaclav Talich, and later under both Karel Sejna and Vaclav Neumann. Their interpretations do vary, in degrees of poetry, exuberance and various other qualities, and the music has the substance to sustain a variety of interpretive approaches. Now the orchestra has made yet another recording of the dances, this time conducted by Zdenek Kosler, and his set (Supraphon 1110.2981/2 ZA) may be the most persuasive yet.

In his 30 years as a conductor, Kosler has made relatively few recordings, and not all of them have been equally impressive. Probably the best until now was his Connoisseur Society coupling (with the London Symphony Orchestra), of Mozart's "Prague" Symphony and six of the Slavonic Dances (available now only on an Advent cassette, E-1025). The dances came off so well that more than a few listeners were eager for Kosler to go home and record the whole cycle. Now that he has done that, one appreciates not only the advances in the recording art in the decade since the Neumann set appeared, but a total identification with this music perhaps unmatched by any conductor since Talich.

Kosler shows no less feeling for the music's poetry than Neumann, but a good deal less sobriety in his general approach. Here the lusty, earthy irruptiveness of the penultimate number (the kolo in C) and the two furiants in Op. 46 not only blaze with vigor and brilliance, but seem to smile with robust good humor. The slower dances -- Op. 46, Nos. 3 and 6, Op. 72, Nos. 2 and 8 -- glow with similar warmth of heart, without becoming sentimentalized. Throughout the cycle, every felicity of Dvorak's scoring makes its point without artificial spotlighting.