"Begotten not made, of one being with the Father"... is a crucial but perplexing phrase in the Nicene Creed. What does it mean, why was it so important (and controversial) and how did we end up with the doctrine of the Trinity? The answers are to be found in the heated 4th century debate which arose following the condemnation of the preaching of a popular Egyptian priest named Arius. Beginning Pusey House’s series of events marking the 1700th Anniversary of the Council of Nicaea, (which will continue in Michaelmas 2025), this Study Day will commence by providing an overview of what Arius taught and why, before examining the initial response of the Church and the text of the original Nicene creed. However, within a few years, the “consensus” reached at Nicaea was rejected by a number of different groups within the Church, and over more than 50 years, the search for alternative formulations continued. Numerous councils were held during this time, often resulting in one or more “better” creeds which were received with varying degrees of success. An overview of a number of these additional councils, and their alternative formulations, will be provided, in order to bring out the different sides of the debate. The end of this period of intense debate and controversy was marked by the classical expression of Trinitarian faith in the creed produced at the council of Constantinople (in 381 AD). The course will therefore end with a comparison of this creed with the one produced at Nicaea. Who is the course aimed at? Anyone who’s read this far and is still interested! A complete lack of previous experience or study is assumed, although clergy, lay readers or others with some knowledge will still find much of interest.