@ThomasFinally, Emperor Constantine wrote to them both (Spring, 325AD):
"So when I found that an intolerable spirit of mad folly had overcome the whole of Africa, through the influence of those who with heedless frivolity had presumed to divide the religion of the people into diverse sects, I was anxious to stop the course of this disorder. After I had removed the common enemy of mankind (Licinius, who was Emperor of the East, and was defeated by Constantine, Emperor of the West) who had interposed his lawless sentence which prohibited your holy synods, I could discover no other remedy equal to the occasion, except to send some of you churchmen to aid in restoring mutual harmony among the disputants." (para 2)
".... now that I have made a careful enquiry into the origin and foundation of these differences, I have found the cause to be of a truly insignificant character, and quite unworthy of such fierce contention. I feel compelled to address you in this letter, and to appeal at the same time to your unity and discernment. I call on Divine Providence to assist me in the task, while I interrupt your dissension as a minister of peace..." (para 4)
"I understand that the origin of the present controversy is this. When you, Alexander, demanded of the priests what opinion they each maintained respecting a certain passage in Scripture, or rather, I should say, that you asked them something connected with an unprofitable question. You then, Arius, inconsiderately insisted on what ought never to have been speculated about at all, or if pondered, should have been buried in profound silence. Hence it was that a dissension arose between you, fellowship was withdrawn, and the holy people were rent into diverse factions, no longer preserving the unity of the one body. And so I now ask you both to show an equal degree of consideration for the other, and to receive the advice which your fellow-servant impartially gives. What then is this advice? It was wrong in the first instance to propose such questions as these, and also wrong to reply to them when they were presented. For those points of discussion are not commanded by the authority of any law, but are rather the product of an argumentative spirit which is encouraged by the idle useless talk of leisure. Even though they may be intended merely as an intellectual exercise, they ought certainly to be confined to the region of our own thoughts, and not hastily produced in the popular assemblies, nor unadvisedly entrusted to the ears of the general public.
For how very few are there able either accurately to comprehend, or adequately to explain subjects so sublime and difficult to comprehend in their nature? Or, granting that one were fully competent for this, how many people will he convince? Or again, who in dealing with questions involving such subtle distinctions as these can be sure he is not dangerously departing from the truth in some point? We ourselves may be unable, through the weakness of our natural abilities, to give a clear explanation of the subject before us, or, on the other hand, our hearers understanding may prevent them from arriving at an accurate understanding of what we say. Lest that be the case, it is our obligation to be sparing with our words, so that neither of these situations will cause the people to be reduced either to blasphemy or to schism." (para 6-8)
"Now forgive one another for both the careless question and the ill-considered answer. The cause of your difference has not been any of the leading doctrines or precepts of the Divine law, nor has any new heresy respecting the worship of God arisen among you. You are really of one and the same judgment; and so it is fitting for you to join in communion and fellowship." (para 9)
Thank you for your valuable and enlightening post. It is well written and researched and professionally presented, as always the result of deep thought and hard work -- in response to the OP of the thread. Your scholarship and intelligence is a great asset to IO