During this retreat Jesus, my blessed Lord, has deigned to give me an even clearer understanding of the necessity of keeping whole and intact my 'sense of faith' and my 'being of one mind with the Church', for he has shown me in a dazzling light the wisdom, timeliness, and nobility of them measures taken by the Pope to safeguard the clergy in particular from the infection of modern errors (the so-called Modernist errors) which in a crafty and tempting way are trying to undermine the foundations of Catholic doctrine. The painful experiences of this year, suffered here and there, the grave anxieties of the Holy Father and the pronouncements of the religious authorities have convinced me, without the need for other proof, that the wind of Modernism blows very strongly and more widely than seems at first sight, and that it may very likely strike and bewilder even those who were at first moved only by the desire to adapt the ancient truth of Christianity to modern needs. Many, some of them good men, have fallen into the field of error. The worst of it is that ideas lead very swiftly to the spirit of independence and private judgement about everything and everyone.
--Pope St. John XXIII, Journal of a Soul, entry from 1910