The Elements of Leaving, Mathews' fourth volume of poetry, follows upon Windfalls (Dolmen 1977), Minding Ruth (Gallery 1983) and According to the Small Hours (Cape 1998), and has been long awaited.

His critic and biographer David Wheatley has this to say of the work:

`It is no exaggeration to say that Mathews does not have themes so much as obsessions. If his Catholic faith provides the ground base for all his work, sexuality, mental illness and the Holocaust recur in poem after poem, stitching together the quotidian and the extreme ... Synthesizing the sexual, the sacred, and the secular, Mathews' poetry is a testament of great personal power, answerable to the cloister and the locked ward, the social lepers and the captains of the ship of state.' (Irish Poetry, Wake Forest 2017)

In these forty-eight remarkable individual poems and sequences Mathews lays out his witness to the travails and joys of youth and old age, to the passing political parade and the intimacies of nature, to the exigencies of parenthood, of frailty and endurance. Informed by a Dublin sensibility, he holds fast to spiritual traditions while testing the parameters and indulgences of the modern world. His voice, by times Keatsian in its lyric penetration, is humanist in its instincts, universal in its reach, and exerts a singularity that leaves no shadow.