Pope Pius X
Pascendi Dominici Gregis §21
Pascendi Dominici Gregis: On the Doctrines of the Modernists
21 Thus far We have spoken of the origin and nature of faith. But as faith has many shoots, and chief among them the Church, dogma, worship, the Books which we call "Sacred," of these also we must know what is taught by the Modernists. To begin with dogma, we have already indicated its origin and nature. Dogma is born of the species of impulse or necessity by virtue of which the believer is constrained to elaborate his religious thought so as to render it clearer for himself and others. This elaboration consists entirely in the process of penetrating and refining the primitive formula , not indeed in itself and according to logical development, but as required by circumstances, or vitally as the Modernists more abstrusely put it. Hence it happens that around the primitive formula secondary formulas gradually continue to be formed, and these subsequently grouped into bodies of doctrine, or into doctrinal constructions as they prefer to call them, and further sanctioned by the public magisterium as responding to the common consciousness, are called dogma. Dogma is to be carefully distinguished from the speculations of theologians which, although not alive with the life of dogma, are not without their utility as serving to harmonise religion with science and remove opposition between the two, in such a way as to throw light from without on religion, and it may be even to prepare the matter for future dogma. Concerning worship there would not be much to be said, were it not that under this head are comprised the Sacraments, concerning which the Modernists fall into the gravest errors. For them the Sacraments are the resultant of a double need - for, as we have seen, everything in their system is explained by inner impulses or necessities. In the present case, the first need is that of giving some sensible manifestation to religion; the second is that of propagating it, which could not be done without some sensible form and consecrating acts, and these are called sacraments. But for the Modernists the Sacraments are mere symbols or signs, though not devoid of a certain efficacy - an efficacy, they tell us, like that of certain phrases vulgarly described as having "caught on," inasmuch as they have become the vehicle for the diffusion of certain great ideas which strike the public mind. What the phrases are to the ideas, that the Sacraments are to the religious sentiment - that and nothing more. The Modernists would be speaking more clearly were they to affirm that the Sacraments are instituted solely to foster the faith - but this is condemned by the Council of Trent: If anyone say that these sacraments are instituted solely to foster the faith, let him be anathema.
Source: Pascendi Dominici Gregis (Vatican.va)