24 Now that we have briefly set out the conditions for ecumenical action and the principles by which it is to be directed, we look with confidence to the future. This Sacred Council exhorts the faithful to refrain from superficiality and imprudent zeal, which can hinder real progress toward unity. Their ecumenical action must be fully and sincerely Catholic, that is to say, faithful to the truth which we have received from the apostles and Fathers of the Church, in harmony with the faith which the Catholic Church has always professed, and at the same time directed toward that fullness to which Our Lord wills His Body to grow in the course of time. It is the urgent wish of this Holy Council that the measures undertaken by the sons of the Catholic Church should develop in conjunction with those of our separated brethren so that no obstacle be put in the ways of divine Providence and no preconceived judgments impair the future inspirations of the Holy Spirit. The Council moreover professes its awareness that human powers and capacities cannot achieve this holy objective - the reconciling of all Christians in the unity of the one and only Church of Christ. It is because of this that the Council rests all its hope on the prayer of Christ for the Church, on our Father's love for us, and on the power of the Holy Spirit." And hope does not disappoint, because God's love has been poured into our hearts through the Holy Spirit, who has been given to us". Each and all these matters which are set forth in this Decree have been favorably voted on by the Fathers of the Council. And We, by the apostolic authority given Us by Christ and in union with the Fathers, approve, decree and establish them in the Holy Spirit and command that they be promulgated for the glory of God. Given in Rome at St. Peter's, November 21, 1964
Source: Unitatis Redintegratio (Vatican.va)