Although, as a rule, scientific books cannot be read to a jury as evidence, they may be read to discredit the testimony of experts, who claim to be familiar with them and refer to them as authority. Where one borrows credit for his accuracy, by referring to books treating of the subject, and by implying that he echoes the standard authorities, the book may be resorted to, to disprove the statement of the witness, and to enable the jury to see that the book does not contain what he says it does, and thus to disparage the witness, and hinder the jury from being imposed upon by a false light [252]. It has been held again and again that scientific books cannot be read by counsel to the jury as a part of their argument. Shaw, C.J., of Massachusetts, says, “Facts or opinions cannot be laid before the jury, except by the testimony under oath of persons skilled in such matters.” Again, “where books are thus offered (_i. e._, to be read in argument), they are, in effect, used as evidence, and the substantial objection is, that they are statements wanting the sanction of an oath; and the statement thus proposed is made by one not present, and not liable to cross-examination. If the same author were cross-examined, and |102| called to state the grounds of his opinions, he might, himself, alter or modify it, and it would be tested by a comparison with the opinions of others. Medical authors, like writers in other departments of science, have their various and conflicting theories, and often defend and sustain them with ingenuity. But as the whole range of medical literature is not open to persons of common experience, a passage may be found in one book favorable to a particular opinion, when, perhaps, the same opinion may have been vigorously contested, and, perhaps, triumphantly overthrown, by other medical authors, but authors whose works would not be likely to be known to counsel or client, or to Court or jury. Besides, medical science has its own nomenclature, its technical terms and words of art, and also common words used in a peculiar manner, distinct from the received meaning in the general use of the language. From these and other causes, persons not versed in medical literature, though having a good knowledge of the general use of the English language, would be in danger, without an interpreter, of misapprehending the true meaning of the author. Whereas a medical witness could not only give the fact of his opinion, and the grounds on which it is formed, with the sanction of his oath, but would also state and explain it in language intelligible to men of common experience. If it be said that no books should be read, except works of good and established authority, the difficulty at once arises as to the question, what constitutes “good authority?” [253].