PRIMER:
Pope Pius X, Lamentabili Sane, Condemning the Errors of the Modernists, #22: "The dogmas the Church holds out as revealed are not truths which have fallen from heaven. They are an interpretation of religious facts which the human mind has acquired by laborious effort." - CONDEMNED.
Pope Pius IX, Vatican Council, Session 3, Chapter 4, ex cathedra: "Hence, too, that meaning of the sacred dogmas is ever to be maintained which has once been declared by Holy mother Church, and there must never be any abandonment of this sense under the pretext or in the name of a more profound understanding."
Any 'understanding' of the dogmatic decrees of the Holy Catholic Church, which in any way recedes from the objective sense of how it was declared IS HERESY. Otherwise you reduce the dogma of infallibility into a meaningless saying.
Pope Leo XIII, Satis Cognitum "The practice of the Church has always been the same, as is shown by the unanimous teaching of the Fathers, who were wont to hold as outside Catholic communion, and alien to the Church, whoever would recede in the least degree from any point of doctrine proposed by her authoritative Magisterium."
Transgressors of these laws are MODERNISTS.