From Pope Pius XII’s encyclical Mystici Corporis Christi (1943):
For while there still survives a false rationalism, which ridicules anything that transcends and defies the power of human genius, and which is accompanied by a cognate error, the so-called popular naturalism, which sees and wills to see in the Church nothing but a juridical and social union, there is on the other hand a false mysticism creeping in, which, in its attempt to eliminate the immovable frontier that separates creatures from their Creator, falsifies the Sacred Scriptures.
As a result of these conflicting and mutually antagonistic schools of thought, some through vain fear, look upon so profound a doctrine as something dangerous, and so they shrink from it as from the beautiful but forbidden fruit of paradise. But this is not so. Mysteries revealed by God cannot be harmful to men, nor should they remain as treasures hidden in a field, useless. They have been given from on high precisely to help the spiritual progress of those who study them in a spirit of piety. For, as the [First] Vatican Council teaches, “reason illumined by faith, if it seeks earnestly, piously and wisely, does attain under God, to a certain and most helpful knowledge of mysteries, by considering their analogy with what it knows naturally, and their mutual relations, and their common relations with man’s last end,” although, as the same holy Synod observes, reason, even thus illumined, “is never capable of understanding those mysteries as it does those truths which forms its proper object.”5
5 Sessio III; Const. de fide cath., c. 4.
— Mystici Corporis Christi 9-10