“This “roccia” (rock) will never crumble, nor flake, given that its solidity is guaranteed in the text of Matthew until the end of time. The “rock” remains and no one will scratch it, implicated as she is in a divine undertaking. But on occasion some men may take from others the vision of the rock. Other things may be made to seem like the rock, other things that may appear to all as such. The distinction is a profound one, even if the errors of these men are capable of veiling the reality (truth), they cannot destroy it. The question, easy for all, that presents itself is one of the visibility of the rock. If then situations should occur, that took from certain men the visibility of the “roccia” (rock) in the Church, the consequences would be grave.Those that convert to the Church, convert because they are convinced that they have found the “roccia” (rock), not doubt, hesitation, contradiction or doctrinal anarchy. One converts when one knows that ones hope is not futile. Taking away the visibility of the “roccia” (rock): what happens?”
— Cardinal Siri, Renovatio II (1967), fasc. 2, pp. 183-184.