On the first Sunday of Great Lent, we celebrate the restoration of the Holy Icons. Following a period of unrest, due to the iconoclastic controversy within the church, Empress Theodora and her son Michael III under Patriarch Methodios held a synod and restored the holy icons and their veneration on the first Sunday in Lent. Ever since, this Sunday has been commemorated as the "Triumph of Orthodoxy."
“As the prophets beheld, as the Apostles have taught, as the Church has received, as the teachers have dogmatized, as the Universe has agreed, as Grace has shown forth, as Truth has revealed, as falsehood has been dissolved, as Wisdom has presented, as Christ Awarded, thus we declare, thus we assert, thus we preach Christ our true God, and honor as Saints in words, in writings, in thoughts, in sacrifices, in churches, in Holy Icons; on the one hand worshipping and reverencing Christ as God and Lord; and on the other hand honoring as true servants of the same Lord of all and accordingly offering them veneration.
This is the Faith of the Apostles, this is the Faith of the Fathers, this is the Faith of the Orthodox, this is the Faith which has established the Universe.
-Confession of faith of the Day of Orthodoxy