If Glidden named a paint color after Leonard Cohen, no question it would be dark. Darker than mulberry, darker even than wine. But not black, a shiny, inert color; rather, something warm and mysterious, alternately mournful and romantic.

Not that the Cohen of "Dear Heather," his 12th studio album since 1967, makes it easy to love him by starting his latest with "Go No More A-Roving." With words by Lord Byron and music by Lord Lenny, it's a high-school slow dance, complete with Motown-via-Ray Conniff background whoo-ers and a cool-as-winter-white-polyester tenor sax. Accept it as ironic, lest you go no more a-roving through the rest of this startlingly beautiful, characteristically challenging album.

He likes to mess with us, this Canadian icon. How else to explain "Morning Glory," a slightly ominous cocktail-bar tune that has him intoning faintly "No words this time? No words . . . Is it censorship? No, it's evaporation."

Cohen employs his speaking voice to great effect throughout the album. "Villanelle for Our Time," a poem by Frank Scott, is read over a dreamy, late-night piano melody, with Anjani Thomas chanting a background vocal as lulling as a warm bath. (It's no coincidence that this call to unity in the face of world disorder should follow "On That Day," Cohen and Thomas's moving, if occasionally peculiar, hymn about Sept. 11, 2001.) Cohen's spoken voice is most effective on "Because Of," an extraordinary piece of self-parody that paints him, drolly and also poignantly, as an aged roue. And on the title track, Cohen and Thomas read, and reread, a brief verse that sounds like the sort of old man's prayer that the British poet John Betjeman might have penned, over a strolling rhythm and a wobbly ballpark organ.

But the man can sing. Indeed, the 70-year-old pipes have developed not only gravitas, but a deeper sensitivity to melody. On "The Faith," based on a Quebecois folk song and featuring Garth Hudson on accordion, Cohen and Thomas blend voices in a rich and strange exploration of religion: "A cross on every hill / A star, a minaret / So many graves to fill." "Nightingale" sounds like traditional folk, perhaps rewritten by Yeats, but is yet another Cohen and Thomas composition, with a bittersweet melody and a lively melody. (And also the album's second Jew's-harp solo, so we don't get too complacent.) "Tennessee Waltz" swings way down into Dixie, with a twangy band (instead of Cohen's frequently used synthesized instruments) and a live audience; recorded in 1985, the faithful cover is an odd coda to this highly original collection.

Maybe it's Cohen's way of proving how much he has grown musically in the past 20 years. But the rest of "Dear Heather" is its own proof of his enduring and stubborn artistry.

Leonard Cohen's pipes have developed gravitas, a deeper sensitivity to melody.