I am not sure when I noticed that “5 against 4” (2010 – 2011) and “Pharynx Dentata” (2010) faced each other from opposite walls, like confident duelers and lifelong partners. Done in enamel on identically sized aluminum panels, the highly concentrated compositions are the result of a visual algorithm in which the forms increased incrementally in height and width as they moved outward from the central, vertical axis—a narrow, empty space—toward the painting’s physical edges. That both paintings are based on a simple rule that Siena adhered to with a ferocious tenacity tempered by unexpected tenderness is not surprising. Rather, it is where this allegiance has led him, as he continues to expand upon the implications of his previous show at Pace. In that 2008 exhibition, Siena’s linear elements, repetition, increment, and pattern had morphed from abstractions into depictions of angry old men made entirely of wrinkles as well as flat, looping, elastic-like forms masturbating themselves and others. At that time, I felt as if the interwoven, unpeopled paradise of Persian miniatures had met the intricately illuminated hell of Northern European medieval art, their screaming and writhing sinners. In “5 against 4,” the artist returns to abstraction, relying on a sequential progression to decide what color to paint a solid band (red, green, blue, yellow umber, and brown-violet), as they increase in height and width, turning methodically towards the edge. Inspired perhaps by the “Temple” paintings of Op artist Richard Anuskiewicz, Siena’s color progression subverts the vibrating optical symmetry of that well-known series, while preserving its basic, recessive structure. As the title suggests, “Pharynx Dentata” invokes human anatomy. The pharynx is the part of the throat that begins directly behind the mouth, and is essential to the digestive and respiratory systems, and to enunciation. The rows and rows of teeth that Siena methodically articulates around the narrow, vertical cavity also recall the many cautionary folktales of the vagina dentate (toothed vagina) that continue to persist in one form or another. Siena’s “Pharynx Dentata” doesn’t repeat that myth of male fear so much as relocate it to the place that connects the individual to speech and digestion, thus making it new. The placement and proximity of “5 against 4” and “Pharynx Dentata” reminded me of Louis Zukofsky’s poetics: “An integral/Lower limit speech/Upper limit music.” What would be equivalent poetics in painting, at least as suggested by these two Siena paintings? Is the upper limit the once lofty realm of abstraction, geometry, and saturated color? Is the lower limit defined by persistent myths, recurring fears and prohibitions about sex and the body? To Siena’s credit, he has not excluded either possibility. In fact, he reaches and, more importantly, redefines both the upper and lower limits through the same vocabulary and methodology: linear elements that repeat according to a set of pre-established rules. Drawing a line is central to everything he does. (If one of the goals of modern and contemporary art has been to go back to the basics, as did the Abstract-Expressionists and the Minimalists, Siena has done so without jettisoning the psychology or the psyche, the dark side of being.) “Malevolent Adolescent Form” is the title of a gouache the artist did in 2010. Geometry is not necessarily benign—it can be used to construct a labyrinth from which there is no escape, driving its inhabitant insane. Siena has many affinities with the authors belonging to the literary group Oulipo (its members included Italo Calvino, Georges Perec, and Harry Mathews), who wrote according to strict rules—a novel that uses no word with the letter “e,” for example. In doing so, Oulipian authors establish their own complex labyrinth within the inescapable one commonly called “reality.” Their motto is that the author is the rat who builds himself a maze from which he sets out to escape. Siena is equally fastidious and thorough. By channeling the conceptual side of Sol LeWitt and the baser preoccupations of R. Crumb, Siena has pushed back against the ghettos and territorial boundaries historians and theorists established long ago in their feeble attempt to herd artists as if they were cows and not cats. Since he first hit his stride more than a decade ago, Siena has been meticulously defining and extending the parameters of his own maze (or oeuvre), knowing there is no escape (something not all artists know or accept) by sticking to his original premise—the line. By drawing simple lines and bands that run the gamut from pure form to decaying flesh, the artist embraces his aspirations and desires, however awkward and disquieting they might be. Rather than passing it off or disguising it, as many artists do, Siena isn’t afraid to communicate deep-seated anger, weirdness, graphic desire, onanistic fantasies, and sagging faces—the male psyche at a little past the midpoint of his life. That he does so in a way that seems collective rather than confessional is just one measure of his increasing mastery.