PERPETUAL WESTBy Mesha Maren Mesha Maren’s novel “Perpetual West” follows her praiseworthy debut, “Sugar Run,” and is sent in the same calculated nonetheless beautiful prose. It begins with a repeated phrase, “they came by way of … ,” which creates a solid musical cadence, guiding the reader via the opening passage like a river present-day. And a river is a vital section of “Perpetual West,” as the novel typically normally takes area on the fraught border between Mexico and the United States, along the Rio Grande. This is the terrain of Cormac McCarthy, Pat Mora, Roberto Bolaño, Cristina Rivera Garza and the Mexican poet Jorge Humberto Chávez. Maren’s authentic descriptions…