28 Thus then, Venerable Brethren, for the Modernists, both as authors and propagandists, there is to be nothing stable, nothing immutable in the Church. Nor indeed are they without precursors in their doctrines, for it was of these that Our Predecessor Pius IX wrote: These enemies of divine revelation extol human progress to the skies, and with rash and sacrilegious daring would have it introduced into the Catholic religion as if this religion were not the work of God but of man, or some kind of philosophical discovery susceptible of perfection by human efforts. On the subject of revelation and dogma in particular, the doctrine of the Modernists offers nothing new - we find it condemned in the Syllabus of Pius IX., where it is enunciated in these terms: Divine revelation is imperfect, and therefore subject to continual and indefinite progress, corresponding with the progress of human reason ; and condemned still more solemnly in the Vatican Council: The doctrine of the faith which God has revealed has not been proposed to human intelligences to be perfected by them as if it were a philosophical system, but as a divine deposit entrusted to the Spouse of Christ to be faithfully guarded and infallibly interpreted. Hence the sense, too, of the sacred dogmas is that which our Holy Mother the Church has once declared, nor is this sense ever to be abandoned on plea or pretext of a more profound comprehension of the truth . Nor is the development of our knowledge, even concerning the faith, impeded by this pronouncement - on the contrary it is aided and promoted. For the same Council continues: Let intelligence and science and wisdom, therefore, increase and progress abundantly and vigorously in individuals and in the mass, in the believer and in the whole Church, throughout the ages and the centuries - but only in its own kind, that is, according to the same dogma, the same sense, the same acceptation.
Source: Pascendi Dominici Gregis (Vatican.va)