By Fr. Joseph Fessio, S.J., Catholic World Report - The Constitution on the Sacred Liturgy, Sacrosanctum Concilium, was one of two documents issued on the same day, December 4, 1963, the first two documents issued by the Second Vatican Council. The other document, Inter Mirifica, is on social communication. Sacrosanctum Concilium is one of the most important documents of the Council, one that has been the least understood and, I believe, has wrought the most havoc – not by having been fulfilled – but by having been ignored or misinterpreted.