It is to be regretted that on many occasions where several medical practitioners have deposed, there has been a direct opposition of opinion:—this difference has sometimes prevailed respecting insanity,[5:A] but more frequently in cases of poison. It is not intended to account for this contrariety of evidence: much will depend on the sagacity of the counsel to institute the proper enquiries; and still more will be incumbent on the medical evidence, in order to explain and establish his testimony. On one side the evidence will be positive; and it is to be presumed that no member of the medical profession would directly state an individual to be insane without being able, satisfactorily to his own reason and conscientious feelings, to exhibit from his conversation, his actions or his writings unequivocal proofs of his derangement. To such well founded illustration, negative evidence would but little avail. [5:A] Vide my Illustrations of Madness. The Lawyers object is the interest of his employer, and for the fulfilment of his duty he is frequently compelled to resort to a severity of investigation which perplexes the theories, but more frequently kindles the irritable feelings of the medical practitioner. This distrust on the part of the lawyer, however unpalatable, is fully justified: most witnesses going into court, not with a wish to be examined, but with the preconcerted intention of _proving_ to a certain extent;—and those most conversant in the history of human testimony, have been extremely scrupulous of admitting it as uniform truth until it has been carefully sifted. Guarded with these precautions and armed with professional experience, the medical practitioner may approach the tribunal of justice with confidence, and advantage to the cause of truth. However dexterous he may shew himself in fencing with the advocate, he should be aware that his evidence ought to impress the judge, and be convincing to the jury. The most experienced physician who has seen insanity in all its forms, and viewed its more delicate shades, must in a question of this nature submit his opinion, to the comprehension and feeling of the ordinary persons who are to appreciate his deposition. Their BELIEF of the alleged insanity must be the test by which his scientific opinion is to be established. That which may be deemed by the medical evidence, clear and unequivocal madness, may not hit the sense of the gentlemen of the long robe, nor carry conviction to the jury.