After Chris Johanson's recent carnivalesque installation, the Portland Art Museum's APEX space returns to more subdued and solemn territory with a show by Montana-based artist Wes Mills. Although Mills' art is predicated on restraint, to describe it as minimalist hardly captures the rigorous restriction in these 24 drawings. Executed on pieces of paper seldom larger than six-inches square, his drawings can be as uncluttered as a single wispy line. At the opposite end of the spectrum, Mills' most laboriously composed surfaces still feel airy and emptied. Even his means are modest: Nearly all of the drawings are created with little more than graphite, powdered pigment, or ballpoint pen. And this reductive strategy is a calculated one. In an interview with the show's curator, Jennifer Gately, Mills explained, "A lot of artists come to their work with ideas. For me, it's the other way around. If one thinks about it, the idea itself would be like another material, another distraction."

Because he refuses to communicate any straightforward message through his drawings, the viewer is left with an almost meditative encounter with sheer form. In fact, looking at these repetitive, hypnotic works, the viewer shares the same sense of quietude and intense focus that Mills presumably experiences as he creates them. In the drawings that contain the least visual information, barely perceptible details—from ghostly erasures to the texture of the paper itself—become critical.

Even his densest compositions, though, snare a viewer's imagination with their evocative openness. In "Haft Rang," a tiny drawing from 1997, he has painstakingly created a field of black, full of shifting grayscale tones. Where Mills has left the surface exposed, two oblong forms seem to hover in the darkness. Strangely, the effect hardly resembles a drawing. Instead, its play between light and dark appears like an unsteady, unfocused photograph taken at night. In his most representational work, an untitled drawing from his Shore Line series, he uses the humblest materials—two pieces of invisible tape, faint graphite marks—to depict the distant horizon line of the ocean and a fiery sun above it. As unassuming as Mills' drawings are, they are nonetheless compelling as a body of work, one which takes simplicity and disciplined practice to nearly monastic lengths.