The book 'Janus' warns us of two duties. The one, to watch against this Gnostic inflation of scientific conceit which is the animus of heresy; the other, to warn all Catholics that to deny the Œcumenicity or the freedom of the Council which the Vicar of Christ has already confirmed in all its acts hitherto complete, or the obligation imposed upon the faithful by those acts, is implicitly to deny the Infallibility of the Church: and that to doubt, or to propagate doubts, of its Œcumenicity and freedom, or of the obligations of its acts, is at least the first step to that denial.