“Let each man then who wishes to be saved believe first in God the first and last, one and three, one in substance, three in character; one in power, three in person; one in nature, three in name; one in Godhead, Who is Father and Son and Holy Spirit, one God, wholly invisible, inconceivable, unspeakable, Whose property it is ever to exist,’since God the Trinity is eternal, for Whom you must not seek a beginning…”
(St Columbanus, Homily 1)