"There was a heedless and unfounded optimism; the capsizing of perspective, which no longer came from above towards what was below, but vice versa with a perspective starting from an unlimited confidence in man; the clouding of the sacred; a false and dangerous irenicism; the spirit of good nature and cooperation with opposing forces; the deconsecration of, and simultaneously, the adoration of certain aspects of creation - above all, of freedom. The Trojan horse was not, properly speaking, the collection of the conciliar documents, but the ideas of certain pressure groups which succeeded in infiltrating the conciliar hall and determining the line of the progressive maturation which consequently flowed out into the post-conciliar culture. The 'sin' of the Council Fathers, therefore, at least the vast majority of them, was not of the formal type 'of full recognition and deliberate consent', but rather the material sin of 'lack of recognition', of levity, of superficial and exaggerated optimism, of good faith on a personal level."
My own (loquitur JWH) view is that the liberals won decisive victories whenever, by craftily arguing that the Curia was trying to dictate to the Council, they managed to persuade the Fathers to discard curial drafts in favour of liberal drafts. We all know how crucial it is to secure the bridgehead of providing the draft which is the basis of discussion; even if you don't always get your way in the ensuing wheeling and dealing, you have at least set the parameters. With luck, you end up with people unhappy about the entire basic culture and presuppositions of the document before them, but reluctantly signing it because they can't quite see what amendments of detail would put things right. That is why - however SSPX tries to get round it - Mgr Lefebvre and very many others did sign the Decree on Religious Liberty while aware they they were being taken for a ride.