From Pope St. Pius X, Pascendi Dominici gregis (On Modernism):
4. But since the Modernists (as they are commonly and rightly called) employ a very clever artifice, namely, to present their doctrines without order and systematic arrangement into one whole, scattered and disjointed one from another, so as to appear to be in doubt and uncertainty, while they are in reality firm and steadfast, it will be of advantage, Venerable Brethren, to bring their teachings together here into one group, and to point out the connexion between them, and thus to pass to an examination of the sources of the errors, and to prescribe remedies for averting the evil.
5. To proceed in an orderly manner in this recondite subject, it must first of all be noted that every Modernist sustains and comprises within himself many personalities; he is a philosopher, a believer, a theologian, an historian, a critic, an apologist, a reformer. These roles must be clearly distinguished from one another by all who would accurately know their system and thoroughly comprehend the principles and the consequences of their doctrines.
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