The progress of dogma is due chiefly to the obstacles which faith has to surmount, to the enemies it has to vanquish, to the contradictions it has to repel. Add to this a perpetual striving to penetrate ever more profoundly its own mysteries. Thus, to omit other examples, has it happened in the case of Christ: in Him that divine something which faith admitted in Him expanded in such a way that He was at last held to be God. The chief stimulus of evolution in the domain of worship consists in the need of adapting itself to the uses and customs of peoples, as well as the need of availing itself of the value which certain acts have acquired by long usage. Finally, evolution in the Church itself is fed by the need of accommodating itself to historical conditions and of harmonising itself with existing forms of society. Such is religious evolution in detail. And here, before proceeding further, we would have you note well this whole theory of necessities and needs, for it is at the root of the entire system of the Modernists, and it is upon it that they will erect that famous method of theirs called the historical.
Still continuing the consideration of the evolution of doctrine, it is to be noted that Evolution is due no doubt to those stimulants styled needs, but, if left to their action alone, it would run a great risk of bursting the bounds of tradition, and thus, turned aside from its primitive vital principle, would lead to ruin instead of progress. Hence, studying more closely the ideas of the Modernists, evolution is described as resulting from the conflict of two forces, one of them tending towards progress, the other towards conservation. The conserving force in the Church is tradition, and tradition is represented by religious authority, and this both by right and in fact; for by right it is in the very nature of authority to protect tradition, and, in fact, for authority, raised as it is above the contingencies of life, feels hardly, or not at all, the spurs of progress. The progressive force, on the contrary, which responds to the inner needs lies in the individual consciences and ferments there – especially in such of them as are in most intimate contact with life. Note here, Venerable Brethren, the appearance already of that most pernicious doctrine which would make of the laity a factor of progress in the Church. Now it is by a species of compromise between the forces of conservation and of progress, that is to say between authority and individual consciences, that changes and advances take place. The individual consciences of some of them act on the collective conscience, which brings pressure to bear on the depositaries of authority, until the latter consent to a compromise, and, the pact being made, authority sees to its maintenance.
With all this in mind, one understands how it is that the Modernists express astonishment when they are reprimanded or punished. – from Pascendi Dominici Gregis (1907)