 He was also involved, with his fellow-Christian Hunayn ibn Ishaq, in an epistolary exchange with the Muslim astronomer, Abu Isa Yahya ibn al-Munajjim, who had invited them to embrace Islam.Both refused, and provided their reasons for rejecting al-Munajjim's Islamic faith.He was named (as Kusta Ben Luka) by the poet William Butler Yeats as a source for the ideas in the poet's philosophical treatise, "A Vision".