Question

excommunicated the king when they disagreed over who should appoint bishops.

Answer 1

One proof of this is one of his most famous works; The Summa Theologica, that Aquinas wrote during his last years, between 1265 and 1274. The work consisted of 3,125 articles in which he presented several reasoning for many of the subjects of Christian theology in the West while he cited many philosophers and religious sources to support their arguments, with the purpose of reconciling faith and reason.