"Hearing Howard Hanson or Leonard Bernstein conduct American music is a pleasure comparable to hearing Pierre Monteux conduct French music or Bruno Walter interpret Mahler and Bruckner. The reading is a one with the writing."

Virgil Thomson, who wrote those words in his 1945 book, "The Musical Scene," expressed his particular pleasure 21 years later with recordings of two of his own works - the "Simphony on a Hymn Tune" and the solo canata "The Feast of Love" - by Hanson and the Eastman-Rochester Orchestra, on a disc which included Hanson's own "Four Psalms" for baritone and strings. These three splendid performances have been reissued in Mercury's "Golden Imports" series of (SRI 75063), and their reappearance is especially timely.

In the three final months of our Bicentennial year, three of our country's most distinguished musical figures turned 80: Howard Hanson on Oct. 28, Virgil Thomson on Nov. 25 and Roger Sessions on Dec. 28. There certainly wasn't much fuss over these anniversaries - a few salutes to Thomson in various cities, but nothing on a truly national scale. In the matter of recordings, the gesture by Mercury would seem to be it.

The disc is enormously welcome, of course, aside from any anniversary context (and there is nothing to indicate that it was reissued in such a context). Thomson's 1928 Symphony is a classic of its kind, an amiable workout on "Jesus Loves Me" in a distinctive style that owes nothing to Ives. The work's absence from our catalogs has been - or ought to have been - a source of national embarrassment. The restoration of the Hanson recording is the most meaningful sort of conservation, for the 1965 sound is as rich and realistic as one might wish, and the performance itself could hardly be more idiomatically persuasive.

Both of the vocal works on Side 2 were introduced at the Library of Congress during the Coolidge Festival in 1964 (I remember Hanson as an endearing figure, bounding on stage to acknowledge the applause of the black-tie-and-evening-gown audience in his lumberjack shirt and non-matching jacket and trousers). The vocal works are quite different from the Symphony. Thomson's cantata is a brief, dry-point setting of his own translation of a marvellous anonymous Latin text, while Hanson's settings of Psalms Nos. 46, 6, 47 and 8 constitute a rugged Old Testament counterpart to Thomson's earlier treatment of the Baptist hymn, laid out in the form of a concerto grosso (concertino sextet and solo cello in addition to the baritone and string orchestra) but thoroughly Hansonian-American in character. Gene Boucher is an effective baritone in the Hanson, David Clatworthy in the Thomson.

Sessions, the odd man out in the aforementioned triumvirate, would seem to have been totally ignored on the occasion of his 80th birthday. The most recent releases of his music on records came a year ago or more, when Mercury reinstated Hanson's recording of the suite from "The Black Maskers," one of Session's most accessible works (SRI 75049), with Barber's "Capricorn Concerto" and Ginastera's "Overture to the Creole Faust"), and Argo brought out the Symphony No. 8 and "Rhapsody for Orchestra) in performances by the New Philharmonia under Frederik Prausnitz (ZRG-702), with Wallingford Riegger's "Dichotomy" and Thea Musgraves's "Night Music").

Not that there aren't gaps to be filled in the Thomson and Hanson discographies. In the case of the latter, Mercury could do most of the filling with further reissues - the old but brilliant mono versions of the Symphonies Nos. 4 and 5, the sumptuous stereo recordings of the First ("Nordic") and Third.

In the Thomson column, we need new recordings of the delicious "Acadian Songs and Dances" (from "Louisiana Story") and some of the orchestral miniatures once offered by Ormandy on Columbia ("The Seine at Night, Wheatfield at Noon," etc.), and it wouldbe good to get around to such unrecorded works as the Flute Concerto, the First String Quartet and the Symphonies Nos. 2 and 3. The Second Symphony has been getting a good deal of live exposure in Erick Hawkin's choreographic treatment (a concert ballet called "Hurrah!"), the Third was well received in its New York premiere (American Symphony under Kazuyoshi Akiyama) last December.