Gilchrist, J.
The question before us is settled by the principle recognized in the case of Woodes vs. Dennett, 12 N. H. Rep. 511. There, the plaintiff, for the purpose of rebutting the defendant’s evidence, offered his book of accounts, verified by his oath, in order to prove that a third person was indebted to him; but the book was held incompetent, because it was offered to prove a fact collateral to the issue between the parties. The reasoning in that case, and the authorities when carefully examined, show that the plaintiff cannot use his book of accounts as evidence, except to prove the cause of action for which the suit is brought. The case of Poultney vs. Ross, 1 Dall. 238, cited in Woodes vs. Dennelt, is an authority upon the point that a book is inadmissible except to charge the original debtor to -whom the goods sued for were sold. The same rule is applicable to a defendant, and he cannot use his book as evidence unless to prove a set-off' against the claim of the plaintiff. In the case of Woodes vs. Dennett, it was not necessary, in stating the reasons for the judgment, to settle or to investigate the particular question that arises here. It is said in that case, that “ without inquiring into the nature of the transaction that may be proved by the book and oath of the party, —.upon which point the decisions are very numerous,—it is sufficient to say that such evidence is confined to suits between the debtor and creditor, whether the claim be made by the plaintiff, or by the defendant by way of set-off.” These remarks were sufficient for that case, because it was necessary to settle only the question whether collateral matters could be proved by this species of evidence. The fact which the plaintiff in the present case desires to prove is a collateral matter, and so far the question is settled by Woodes vs. Dennett, in terms; but the particular shape it assumes, *26from the alleged error, calls for a further exposition of the principle. The exact question is, whether, in an action upon a promissory note given for the balance appearing to be due upon an account stated, the plaintiff may rebut the defendant’s set-off, by showing by his books, verified by his oath, that the account was erroneous. In order to do this, he must be permitted to give a history of the transactions connected with the disputed matter, more or less minute, as the particular case may require. If such a principle were recognized, it would make the party a witness to an extent far exceeding the limits which the law contemplated in permitting the party to testify at all. In the complicated affairs of an extensive business, and investigations into such affairs, afford the surest tests of rules of evidence, the practical effect of admitting the party to testify about collateral matters would be, that the simple rule prescribing the questions to be put him, would be entirely lost sight of, and the cautious principle, that no party should be a witness in his own cause, would no longer regulate trials where matters of this kind were inquired into. The explanation of a mistake in his books would often require a detailed statement of numerous circumstances connected with the business of the party, which he only could know, and of which he could give such a version as he pleased, without fear of contradiction. Such a temptation the law very wisely refuses to hold out to litigants, and we have no disposition to extend the rule beyond what we believe to have been its original and legitimate object, it is the book which is the evidence, and the party testifies in chief only to verify it. The party is not a witness who testifies to facts, and then appeals to his book in corroboration of his story, but the book is the source of information, and the party is limited to testifying that it is a true record. If he be permitted to go beyond this, and to modify what is there written, and to explain errors, he will become the source of information, and his book will occupy but a secondary position. He will testify in his own case, like any *27other witness, and to this, or to any principle leading to this, the policy of the common law is decidedly opposed. This, we think, is a strong argument against the admission of the evidence, and the judgment of the court is that it was incompetent.
Verdict set aside.