If the Church is to be regal, a witness for Heaven, unchangeable amid secular changes, if in every age she is to hold her own, and proclaim as well as profess the truth, if she is to thrive without or against the civil power, if she is to be resourceful and self-recuperative under all fortunes, she must be more than Holy and Apostolic; she must be Catholic
The same site features a letter from Pius XII on the centenary of Newman's conversion:
One quality especially seems to Us to call for close attention and study in the career of the great man whose happy return to the Christian fold you are commemorating. He ‘gave up his whole life to the truth’ (Juvenal. Sat. iv. 91); all his efforts, all his untiring labours, were dedicated to that end. A time came when the beauty of Catholic teaching revealed itself clearly to his longing eyes; with that, no obstacle of any kind—his old prejudices, loss of prospects, the protests of his friends—could hold him back; nothing must stand between him and full adherence to the truth he had now mastered. He held to it ever afterwards with unshaken consistency, made it the guiding principle of his whole life, found in it, as in nothing else, full contentment of mind.
‘The mind,’ we are told, ‘knows no food more appetizing than discovery of the truth’ (Lactantius, De Falsa Religione, i. 1; Migne, P.L. VI, c. 118). What shall we say, then, of truth in matters of religious belief, so intimately bound up with every man’s hope of eternal salvation? To search out such truth as this with all care, hunt it down with all eagerness, is a task for great and generous hearts; to possess it fully, is to win enlargement and satisfaction of mind. There can be no doubt that the evocation of so great a memory will have great value for those who already rest in the bosom of the Catholic Church, already enjoy Christian teaching in its entirety. read the rest here