https://en.wikipedia.org/wiki/First_...nical_Councils
First Council of Nicaea (325)
First Council of Constantinople (381)
First Council of Ephesus (431)
Council of Chalcedon (451)
Second Council of Constantinople (553)
Third Council of Constantinople (680–681)
Second Council of Nicaea (787)
https://www.youtube.com/watch?v=9PNZSGeTNoI
