He didn't change that much, it was the Church that changed.

I am old enough to remember Vatican II, which started when I was a sophomore in high school. It was a time when many of us were filled with idealism and hope. As Wordsworth said about the time of the French Revolution, "Bliss was it in that dawn to be alive, But to be young was very heaven!" Now, I know what happened to the ideals of the French Revolution -- the red terror, the white terror, the Gironde, etc. The idealism, the hope of that revolution was lost; and the idealism, the hope of the late 60s, early 70s was lost also. I will not speak of the political reasons for losses for people like me -- Viet Nam, Kent State, Watergate; but our idealism and hope was also in our Church.

We felt a spirit saying "Behold! I make all things new!" -- and yes, some of us went overboard. I have never been to a Mass where beer and pretzels were consecrated (we all heard about such things, but no one AFAIK ever actually saw one) but I have been to a Mass concelebrated by a Catholic priest and an Episcopalian priest, and we were expecting full reunion between Rome and Canterbury because each Church would recognise the other as sisters in Christ. "Strive for peace with everyone, and for that holiness without which no one will see the Lord. See that no one be deprived of the grace of God" (Hebrews 11:14-15) Perhaps we were foolish to think such things -- no, not perhaps, we were foolish. We believed that centuries of tradition (note, I am using tradition with a small "t", decades of disdain for "lesser breeds without the law", and reams of polemics could be overcome in a fortnight. Not to mention a thoroughly entrenched Church bureaucracy, which fought tooth and nail for its vision of the Church.


So, what happened? Well, a lot of things, starting with Humanae Vitae
and its repercussions.