Entirely worth the trip to SECCA, however, is Devorah Sperber's "Virtual Environment 1," an 8-by-28-foot wall construction featuring 20,000 spools of Coats and Clark thread in a subtle range of pastel hues. Talk about a difficult medium! Like the dabs of paint in an impressionist painting when viewed too closely, this piece makes little sense up close, other than as a display of an awful lot of spools. Back a way and squint a little and the dabs of beige, gray, peach, blue and lavender reveal a large and quite beautiful "painting" of stones in a mountain stream. Sperber's vision is remarkable. It brings to mind a monumental worm's-eye view by photographer Ansel Adams of a rock-filled mountain stream. Sperber's subtle construcion has all the necessary artistic conventions: originality, skilled delineation, control of the medium, a unified, pleasing palette. All that's missing is a message (unless you are one who finds sermons in stones), and that omission, in this case, is sort of welcome!