prompter: Thank you! Could you please put the summaries after a line break?

assistant: Sure! 
First Council of Nicaea (325) 
- Called by Emperor Constantine to resolve the Arian controversy, which challenged the orthodox doctrine of the Trinity. The council affirmed the divinity of Jesus Christ and produced the Nicene Creed.

First Council of Constantinople (381) 
- Called to deal with the issue of Arianism and the nature of the Holy Spirit. The council affirmed the divinity of the Holy Spirit and revised the Nicene Creed to include a fuller expression of the Trinity.

Council of Ephesus (431)
- Called to address the teachings of Nestorius, who denied the unity of Christ's divine and human natures. The council affirmed the doctrine of Mary as "Mother of God" and condemned Nestorianism.

Council of Chalcedon (451)
- Called to address the issue of the nature of Christ and the teachings of Eutyches, who believed that Christ had only one nature. The council affirmed the doctrine of two natures in Christ, fully divine and fully human.

Second Council of Constantinople (553)
- Called to address the teachings of Nestorianism and the Three Chapters controversy, which had caused division in the Eastern Church. The council affirmed the orthodox doctrine of the Trinity and condemned Nestorianism and the Three Chapters.

Third Council of Constantinople (680-681)
- Called to address the teachings of Monothelitism, which denied that Christ had two wills (divine and human). The council affirmed the doctrine of two wills in Christ and condemned Monothelitism.

Second Council of Nicaea (787)
- Called to address the issue of iconoclasm, which had caused division in the Eastern Church. The council affirmed the use of icons in worship and condemned iconoclasm.

Fourth Council of Constantinople (869-870)
- Called to address the issue of Photianism, which challenged the authority of the pope and the Western Church. The council affirmed the authority of the pope and condemned Photianism.

First Lateran Council (1123)
- Called to address issues related to the investiture controversy, which involved the power struggle between the pope and the Holy Roman Emperor. The council affirmed the pope's authority in the appointment of bishops and other church officials.

Second Lateran Council (1139)
- Called to address issues related to clerical celibacy and the Holy Roman Emperor's interference in Church affairs. The council affirmed the practice of clerical celibacy and condemned the Holy Roman Emperor's interference.

Third Lateran Council (1179)
- Called to address issues related to the election of popes and the regulation of Church affairs. The council established procedures for the election of popes and affirmed the authority of the pope in Church affairs.

Fourth Lateran Council (1215)
- Called to address issues related to the nature of Christ and the authority of the Church. The council affirmed the doctrine of transubstantiation and established the sacrament of confession.

First Council of Lyon (1245)
- Called to address issues related to the power struggle between the papacy and the Holy Roman Empire. The council affirmed the pope's authority over the Holy Roman Empire and established the office of papal legate.

Second Council of Lyon (1274)
- Called to address issues related to the power struggle between the papacy and the Holy Roman Empire, as well as the issue of the Filioque clause in the Nicene Creed. The council affirmed the pope's authority over the Holy Roman Empire and established a temporary union between the Eastern and Western Churches, but this union ultimately proved unsuccessful.

Council of Vienne (1311-1312)
- Called to address issues related to the Knights Templar and the role of the papacy in Church affairs. The council condemned the Knights Templar and affirmed the pope's authority over Church affairs.

Council of Constance (1414-1418)
- Called to address issues related to the Great Schism, which had caused division within the Church. The council deposed three rival popes and elected a new pope, thus ending the Great Schism.

Council of Basel/Ferrara/Florence (1431-1445)
- Called to address issues related to the power struggle between the papacy and the Holy Roman Empire, as well as the issue of the Filioque clause in the Nicene Creed. The council established a temporary union between the Eastern and Western Churches, but this union ultimately proved unsuccessful.

Fifth Lateran Council (1512-1517)
- Called to address issues related to Church reform and the threat of the Ottoman Empire. The council established reforms in Church governance and affirmed the need to defend against the Ottoman threat.

Council of Trent (1545-1563)
- Called to address issues related to the Protestant Reformation, which had caused division within the Church. The council affirmed Catholic doctrine on the Eucharist, the sacraments, and justification, and established reforms in Church governance and discipline.

First Vatican Council (1869-1870)
- Called to address issues related to the role of the papacy and the relationship between faith and reason. The council affirmed the doctrine of papal infallibility and the Church's authority in matters of faith and morals.