It's no secret that a major part of the reason for John XXIII's being declared a saint was his role in calling the Second Vatican Council. Here is what he intended:
"[The Second Vatican Council… wishes to transmit the doctrine, pure and integral, without any attenuation or distortion, which throughout twenty centuries, notwithstanding difficulties and contrasts, has become the common patrimony of men. It is a patrimony not well received by all, but always a rich treasure available to men of good will… The salient point of this Council is not, therefore, a discussion of one article or another of the fundamental doctrine of the Church which has repeatedly been taught by the Fathers and by ancient and modern theologians, and which is presumed to be well known and familiar to all.
For this a Council was not necessary. But from the renewed, serene, and tranquil adherence to all the teaching of the Church in its entirety and preciseness, as it still shines forth in the Acts of the Council of Trent and First Vatican Council, the Christian, Catholic, and Apostolic spirit of the whole world expects a step forward toward a doctrinal penetration and a formation of consciousness in faithful and perfect conformity to the authentic doctrine, which, however, should be studied and expounded through the methods of research and through the literary forms of modern thought. The substance of the ancient doctrine of the deposit of faith is one thing, and the way in which it is presented is another. And it is the latter that must be taken into great consideration with patience if necessary, everything being measured in the forms and proportions of a magisterium which is predominantly pastoral in character."- Pope John XXIII, Address to Open Vatican II
Before the day was out, the Council Fathers, the bishops, would tear up all of Pope John's plans for the Council (the Schema) and throw them in the trash. He died seven months later. It's documented here.