The “Living Tradition” of the Church is not a human invention but the guidance of the Holy Spirit throughout history, most clearly seen in the Ecumenical Councils and the writings of the Church Fathers.
The Seven Ecumenical Councils were world gatherings of bishops to rule on questions of doctrine and discipline. These councils are considered infallible by the Orthodox Church because they accurately teach the truth handed down from the Apostles—from the First Council of Nicaea (325 AD, affirming Christ is truly God) through the Second Council of Nicaea (787 AD, defending the veneration of icons as a witness to the Incarnation).
The Church Fathers—including St. Basil the Great, St. Gregory the Theologian, and St. John Chrysostom—are the saints whose lives and writings provide the key to correctly understanding Scripture. They are the “spiritual vitamins” for the soul, ensuring the Church remains faithful to what was given once and for all rather than discovering supposed new truths.