Not every valid council in the history of the Church has been a fruitful one; in the last analysis many of them have been just a waste of time. Joseph Ratzinger, 1987.
The missed opportunity to which I refer in my heading was the 700th anniversary, in 2011, of the Convocation of the Holy Ecumenical Council of Vienne. (Oh dear, what is the proper term for a 700th anniversary?)
This great event could have been celebrated throughout the Church; and, particularly, in her educational life. Pushy young clerics aiming to advance their careers by the acquisition of a JCD could have written dissertations on The Magisterial significance of the lost Decrees of the Council of Vienne. Seminarians could have been set essays on The Spirit of the Council of Vienne: a sure guide for the Church in her Third Millennium. Sixth Forms would have been enlightened by examination modules (taught by a collaboration between the Theology and Economics Departments) on Embezzlement: its theological basis and its practical implementation. In the Church's Primary Schools, where the education is less conceptual and more vivid, teaching materials from the Bishops' Conference education offices would have concentrated on How to burn your own Templar.
I feel an urge coming on to devote a few posts to Ecumenical Councils. They may probably be in the spirit of Joseph Ratzinger's wise words. Or of Gregory Dix? Or of John Henry Newman? No; of all three.