Tibetan Buddhists often meditate on bardo, a transitional state between life, death, and rebirth. The sense of hovering between the end and a new beginning runs through The Blue Hour, a cycle of 40 songs co-written by Rachel Grimes, Angélica Negrón, Shara Nova, Caroline Shaw, and Sarah Kirkland Snider for singer-songwriter Nova and A Far Cry, the Boston-based, self-conducted chamber orchestra. The work takes its lyrics from “On Earth,” a long poem by Carolyn Forché that recounts the thoughts of a dying woman and uses them to cultivate genuine feelings of universal empathy. Its miniature movements include heartfelt ballads, echoes of Bach and Abbess Hildegard (in Caroline Shaw’s mesmerizing Firmament), haunting laments, operatic cadenzas, punchy incantations, and much else, the whole proving greater than the sum of its considerable parts.