We say, then, the church is herself the witness, and a competent and credible witness, to her own divine commission to teach and declare the word of God which he has revealed, and no better, no more competent or credible witness is needed or, in fact, conceivable. She is competent because she is the identical apostolical body, the contemporary and the eye-witness through the successive ages of the facts to which she testifies. She is a credible witness, because even as a human body it would be hardly possible for her either to mistake or to misrepresent the facts to which she testifies, since they are always present before her eyes, since, however her individual members may change, she herself knows no change with lapse of time, and no succession. She could not forget the faith, change it, or corrupt it, because there is at all times in her communion an innumerable body of living witnesses to its unity, purity, and integrity, who would detect the change or alteration and expose it. It is not with her as it would be with a book having a limited circulation. Copies of the book could easily be altered or interpolated without detection; but the living testimony of the church, spread over the whole world and teaching all nations, cannot be interpolated or corrupted. It is on the fidelity of the church, her vigilant guardianship, and uniform testimony that we depend for our confidence in the genuineness and authenticity of our copies of the sacred writings, and it is worthy of note that in proportion as men throw off the authority of the church, and reject her traditions, they lose that confidence, and fail to agree among themselves what books, if any, are inspired; so that without the testimony of the church the Holy Scriptures themselves cease to be an authority in matters of faith.
In human tribunals the supreme court is presumed to know the law which constitutes it, and it defines its own jurisdiction and powers. It declares the law of which it is the depositary and guardian, and though the judges have only their human wisdom, learning, and sagacity, it is remarkable how few mistakes through a long series of ages they commit as to what is or is not the law they are appointed to administer, and nearly all the mistakes they do commit are due to the changes the legislature makes in the law or in the constitution of the court. Why should the church be less competent to judge of the law under which she is constituted, and to define her jurisdiction and powers? And since her constitution, as well as the law she administers, changes not, why should she be less exempt, even as a human court, from mistakes in interpreting and declaring the law, than the supreme court of England or the United States? What higher authority can there be to judge of her own constitution and the law given her to administer than the church herself?