In his song, "Flow my tears," Elizabethan composer John Dowiand reached a level of musical intensity comparable to the verbal power in some of Shakespeare's best scenes. Then, like Schubert with his songs, "The Trout" and "Death and the Maiden," feeling that the motifs of his song had still more musical substance that needed exploration. Dowland used it as the basis for a series of instrumental elaborations.

Written for viols and lute, and finally published as "Lachrimae, or Seaven Teares Figured in Seaven Passionate Pauans," the result is a landmark in music history. the most sustained, unified and elaborate instrumental composition by any English composer before Purcell.

An excellent new recording has appeared: "John Dowland: Lachrimae 1604 ." performed by The Consort of Musicke,u - Lyre DSLO 517). and bearing it sets up some curious resonances. The music will remind some listeners of Bach's final Brandenburg COncerto with its mocochromatic instrumental color, or of Shostakovich's final string quartet with its daring use of an unbroken series of slow movements and its melancholy, reflective style.

These are the most ready comparisons, but "Lachrimae" is quite unusual. It will appeal primarily to those who have been captivated by the song on which it is based, but others might try it to discove whether they share this specialized taste. The miscellaneous pavans, galliards and other pieces recorded on side two were originally published with "Lachrimae" but have somewhat less intense or unified impact.

A few other recordings of interest to those who care for early musical instruments are noted briefly.

"The Renaissance Clavichord." Works of Attaignant, Newsidler, Milan and others. Bernard Brauchli, clavichord (Titanic Ti - 10). The gentlest - voiced and most delicately nuanced of all the keyboard instruments, with strings that are struck (like a piano's) not plucked (like a harpsichord's), the clavichord is mainly an instrument to be heard in the home, since its sound is lost in any concert hall much larger than a telephone booth. Records are its ideal medium, and this beautifully played, subtly recorded collection of works by little - known Renaissance composers is one of the finest I have heard. Several local record shops carry Titanic Records, but if you have trouble finding it, the company's address is 43 Rice St., Cambridge, Mass. 02140.

"Historic Instruments in Performance." Giustini& Sonata No. 8 for fortepiano. C.P.E. Bach: Music for unaccompanied flute, flute with continuo and clavier. James Bonn, fortepiano and harpsichord; David Hart, baroque flute (Pleiades P 105). The Giustini sonata is pleasant, undistinguished and important because it is a part of the first opus ever published (in 17321) specifically for the piano. The C.P.E. Bach works are musically more substantial but given added interest here by the instruments on which they are performed - various keyboard instruments and a very beautiful - sounding porcelain flute from the Metropolitan Museum's collection. The performances are excellent, and this record (produced by the Soutern Illinois University Press) should be part of the basic recorded documentation in any collection that allows room for the sound of untampered old instruments.