Intense hues evenly inhabit the circular forms: clear orange, a lush green, a glowing violet and other highly saturated colors. They seem to be handsome, uncomplicated paintings and indeed the sense of handsomeness persists. As one begins to compare the twenty-six large acrylic paintings, marked differences assert themselves and the works become increasingly complex. In each painting, the main axis shifts slightly and each circle sequentially becomes a different color. ... Suddenly, the circular format seems to become spherical and the viewer discovers spatial progressions while also responding to an absolutely flat color shape surface. Simultaneously, color and form appear to project from the canvas like a cone or, conversely, to deeply recede, yet at the same time a flat rhythm is established across the surface of the canvas. Each painting then begins to evidence itself as a complete universe ... and achieves a fresco look so that the circular color form image does not separate from its square white background and become an object. Each color area contains four to six coats of paint and a single canvas may hold a load of seven quarts of paint. Aach refers to these works as "sequential serialized color form painting" and the show itself is called Precession of the Equinox. The latter title refers to the tendency of the the paintings to have a color expansion (or color pull) towards the west, just as the earth itself has a westward drift and an eccentric off-center equinox because of its particular shape. While thoroughly programmed, individually and together, Aach´s paintings do not elicit a computerized response. It is astonishing that they eventually reveal themselves as systems because the viewer is instantly caught up in color activity. Remnants of the artist´s pencil drawings remain at the edges of the paintings, as if to underscore the personal working process that lies behind the programming. As we expect accelerated and intensive color experimentation during the next decade, Aach is indeed a pioneer.
from Noel Frackman in review of Precession of the Equinoxes at Martha Jackson Gallery, New York, in Arts Magazine, Sept. 1974, p.74.

Herb Aach (1923–1985) was an American painter and writer. Aach´s painting style is known for its intense and well placed pigmentation, which stemmed from his deep interest in color theory and color relationships. Herb Aach was born in Cologne, Germany in 1923. He studied under German expressionist painter Ludwig Meidner. Nazi persecution caused his family to flee, and in 1938 he arrived in New York City. In 1942 he enlisted in the United States Army and a year later he became a U.S. citizen. After serving during World War II, in Kassel, Germany, he returned to New York in 1946 where he studied under John Ferren and Rufino Tamayo at the Brooklyn Museum Art School. In 1948 he moved, with his new wife, to Mexico City where he continued his fine art studies at Escuela de Pintura y Escultura.