Two of his long poems, Advent (1975) and Death of Hektor (1979), were widely considered to be important works in the canon of Irish poetic modernism.
In his 1934 essay Recent Irish Poetry, Beckett picked out Coffey and Devlin as forming 'the nucleus of a living poetic in Ireland'.
He entered the Institut Catholique de Paris that year to work with the noted French philosopher Jacques Maritain, taking his licentiate examination in 1936.
On trips home to Dublin, he contributed to programmes on literary topics on RTÉ radio and published poems in Ireland Today.
The poems of this period saw Coffey shake off his earlier influences and begin to find his own voice but, for a variety of reasons, Third Person was to be his last poetry publication for a quarter of a century.
During this period, Coffey seems to have done very little, if any, creative writing as he focused mainly on philosophical work based on his thesis, publishing a number of essays in The Modern Schoolman.
By the early 1950s, Coffey had become uncomfortable for a number of reasons, including the nature of his work, his distance from Ireland and the pressures that inevitably came to bear on an academic who had previously associated with well-known left-wing writers in Paris.
For these reasons, he began to look for a suitable opportunity to leave the United States and resigned, possibly on a matter of academic principle, in 1952.
He learned printmaking and produced a good deal of original work, including an interesting set of images based on the plays of his old friend Beckett.
These two published poetry, prose and translations by Coffey in their journal The Lace Curtain, and his Selected Poems (1971), under their New Writers Press imprint.