Most New Yorkers don’t think very much about the J. Pierpont Morgan library’s long affiliations with the Metropolitan Museum of Art. Indeed, because the Library has been closed since May 2003 for renovation and expansion (it is scheduled to reopen on April 29), many of us may not think of it at all.

Yet financier and collector J.P. Morgan (1837-1913), who amassed an astonishing collection of more than 3,000 medieval objects, 1,200 Mesopotamian cylinder seals, and 600 illuminated manuscripts, was once president of the Met. Its own holdings include many works formerly in his collection.

A handful of Morgan’s medieval masterpieces from the Library’s treasury, which have been on longterm loan to the Met and are on view in the museum’s Medieval Tapestry Hall, will go back into hiding for another four months on Sunday. So now is your last chance to see this part of Morgan’s collection reunited.

In 1917, his son, J.P. Morgan Jr., donated roughly 7,000 chiefly ancient and medieval objects from Morgan’s collection to the Metropolitan Museum. Other items were sold, or donated to Hartford’s Wadsworth Atheneum, the home of J.P. Morgan’s birthplace. Morgan Jr. kept together his father’s illuminated manuscripts, books, and drawings, and his favorite paintings, treasury objects, documents, and cylinder seals for the Morgan Library.

The Metropolitan’s treasure-trove grouping – a bit of an incredibly shrinking exhibition (its original seven objects had dwindled to five when I saw them on Tuesday) – is still worth a special trip. Sadly, the exhibit no longer includes Morgan’s most famous of objects, the “Stavelot Triptych” (mid-12th century), which was originally made as a reliquary of the True Cross. But the remaining objects are out of this world and will whet your appetite for the library’s long-awaited reopening.

These include two elaborate ciboriums (objects that were used to hold the Eucharistic wafers) in champleve enamel and gilded copper: the hexagonal “Klosterneuberg Ciborium” (German or Austrian, c. 1270-1300) and the round “Malmesbury or Morgan Ciborium” (English, c. 1160). The former illustrates the Four Evangelists and Christ’s Passion.The latter depicts, in circular motifs, scenes from the Old Testament on the bowl and scenes from the New Testament on the lid, making it seem as if the New were spiraling or opening out of the Old.

Also on view is the elaborate “Basin Portable Shrine” (French, 1320-40) in silver gilt, enamel, and precious stones, a hinged, miniature Gothic chapel that, when open,shows a beautiful sculpture of the Madonna and Child; and “Le Roi Bourges” (c. 1230), a standing, high relief sculpture of the king in repousse gilded silver with jeweled crown, framed with red velvet.

The real show-stopper, though, is the “Lindau Gospels” (770-90; c. 880; with additions in 1594).The resplendent twosided book cover, a gleaming, elaborate array of emeralds, sapphires, pearls, topaz, garnets, champleve enamel, gilded copper, silver, and gold repousse, is one of the most beautiful objects in New York. It has the power to remind you of what we have been missing and of what, come the end of April, waits in store.

It alone makes the case for why the Morgan Library is one of New York’s greatest, and most sorely missed, treasures.

Until January 8 (1000 Fifth Avenue, at 82nd Street, 212-535-7710).