3. We use the Fathers as evidence of the _doctrine_ which was taught by the Church, in their own and preceding ages. And here some of the remarks just made will apply again. The Fathers, like all other writers, sometimes state their own individual opinions, or the views of doctrine which prevailed in the sect or party to which they were attached, or in the particular part of the Church in which they were placed, or in the age in which they lived: at other times, and more frequently, the doctrines of the whole Church, in their own and all preceding ages. Now, where a writer states that what he is saying is held by the whole Church, unless we know any thing to the contrary, it is reasonable to believe that it was the case; because we know that the tradition of doctrine was, for the most part, jealously kept up by the perpetual intercourse and communication between the bishops of the several churches. And so again, where a writer affirms that any particular doctrine has been handed down from the beginning, unless we have opposing evidence, it is reasonable to take his word; because we know that it was the custom and practice of the whole Church to require every new bishop to confess the doctrine _already received_, and to teach its doctrines to new converts as already received. And, at all events, such a statement is conclusive evidence, that such doctrine had come down from a generation or two preceding that of the writer; unless (as was said before) we have proof to the contrary. But, as has been already stated, it is possible for an individual to be led away by controversy, or prejudice, or party bias; and therefore, when he is manifestly under any such influence, it is well to be on our guard. For that and other reasons, in any matter of serious doubt, it is impossible to rest upon the word of any single writer; but we use him as a link in the chain of evidence as to the doctrine taught from the beginning by the united universal Church.