Nature is not only celebrated in Castle’s poetry, but suffused with a sense of the sacred. Her use of the title word ‘triptych’ is telling: a triptych (from the Greek triptykhos meaning ‘three-layered’) is an artwork in three parts, usually religious. As a convent-educated daughter of Irish Catholic immigrants to England, she is well versed in church traditions, and her poetry is steeped in a sense of the liminal, of finding herself hovering on the thresholds of worlds—the secular and the spiritual, Ireland and England.