1. The court are of opinion that the opinion of the physician should have been admitted. We think the settled practice in this commonwealth has been to admit the opinion of educated, practising physicians upon subjects of medical _science. Until quite a recent period, the disease of insanity has not been made a specialty. That it is now made a special study by a small number of physicians may be a good reason for giving to their opinion greater weight; but it is not a sufficient reason for excluding the opinions of other physicians. It is well known that various classes of diseases, as those of the spine, the eye, the ear, the skin, have become specialties, especially in our larger cities, where such division of labor becomes practicable. But this fact does not render incompetent upon these subjects the testimony of other physicians, who must necessarily have less experience. The difference is in the weight, rather than the competency of the testimony.
Even upon the matter of weight, there are one or two suggestions which will not escape the attention of those reflecting *79upon the subject. Those who have been accustomed to try issues involving the sanity of testators, their capacity to make wills, will have observed that in a large proportion of the cases the alleged want of capacity is in the infirmity and decay of the faculties, resulting from old age, or the weakness and prostration of disease, or from the two combined. The cases of distinct delusion are quite rare and exceptional. The far greater number of issues as to sanity therefore fall within the ordinary range of a physician’s practice. A physician of large experience could scarcely be found, who had not been often called to consider and form an opinion upon the capacity of his patients to make wills. Supposing the question was as to the gradual decay of the faculties of the testator from disease or old age, one cannot but see that the opinion of an intelligent family physician, familiar with his patient’s infirmities, and watching them at every stage of their progress, would and should have far greater weight with a jury than that of any number of physicians who had made insanity a special study, but who were called to give an opinion upon what is always, and necessarily, an imperfect statement of the facts and symptoms. Or, if the case were one of an original defective capacity, the judgment and opinion of the old family physician would be worth more than that of the masters of the science of insanity, who can have but a fragment of his history.
All lawyers know how difficult it is to try issues of sanity with the restrictions as to matters of opinion already existing; how hard it is to make witnesses distinguish between matters of fact and opinion on this subject; between the conduct and traits of character they observe, and the impression which that conduct and those traits create, or the mental conclusion to which they lead the mind of the observer. If it were a new question, I should be disposed to allow every witness to give his opinion, subject to cross-examination upon the reasons upon which it is based, his degree of intelligence, and his means of observation. It is at least unwise to increase the existing restrictions.
To adopt the limitation made by the rule of the presiding *80judge would be to confine opinion on questions of insanity to those physicians who have made insanity a special study and pursuit. As most cases of insanity are treated in hospitals and public institutions, the limitation would practically confine parties to physicians who were or had been engaged in those institutions. The number of these is so small, and their attendance so difficult to be procured, that the limitation would be in effect an exclusion of matters of opinion upon subjects where it is difficult even for the best trained minds to distinguish and adhere to the line which separates opinion from fact. For with respect to the powers and faculties of the mind, it is obvious, we can directly know nothing. We know them only as they are manifested in action.
Nor, if the opinions of persons who have made the subject of mental disease a special study could be had, would it be wise to limit matters of opinion exclusively to them. Large as is the debt which science and humanity owe to them, great as are the advantages which spring from the devotion of the- mind to a special study, a not infrequent result is—what it used to be said was the mark of a good judge—a tendency to enlargement of jurisdiction. As it is, it cannot be wholly avoided.
To put upon the stand a skilful physician, (and such an one has never understood the bodies of his patients unless he has known also something of their minds, and the action of one upon the other,) to get from him the history of his patient, the state of his bodily health, his conversation, conduct, traits of character in sickness and in health, and then to exclude the opinion which, as the result of all, his mind has almost insensibly and necessarily formed, and yet, upon this imperfect history of his patient, to ask a perfect stranger to that patient to give his opinion of his mental condition, because he has made mental disease a special study; would be to reject the most valuable evidence, for that which, in the nature of things, must be of far less worth. Upon a subject of such intrinsic difficulty, the jury should have the aid and assistance of both.
In the case at bar, the doctor had been the medical adviser of the deceased, as well as a physician of experience. The precise *81point decided is, that his opinion as to the sanity of his patient should have been admitted in evidence.
It is suggested in the argument of the appellees, that the question whether the witness is an expert or not is, under all the facts, one to the discretion of the court. In this case, it is sufficient to say the facts are reported and the point reserved by the presiding judge. But the decision involves not merely a judgment upon the facts before the judge, but a general rule applicable to the trial of all similar causes. It is therefore a question of law for the consideration of the whole court.
2. The appellants’ counsel offered to show by the same witness that the testator’s family, both on his father’s and mother’s side, were subject to insanity, and that his father and mother and an uncle of his were insane. But the presiding judge ruled that the testimony to these facts was inadmissible.
We think the practice has been to admit such evidence. See, among other cases, Trial of Rogers, 144. We think the practice is right in principle. It rests upon the ground of the hereditary character of insanity, that a predisposition to the disease is frequently transmitted from parent to child. With such predisposition, the malady may not show itself in the child; for the child may not be exposed to any exciting cause. But with such hereditary taint, insanity supervenes from slight causes— causes apparently wholly inadequate to affect a mind without the predisposition. In making a diagnosis of such a case, we suppose that among the first questions which would be put would be, whether the parents of the patient were or had been insane. With the fact that the father and mother, or either of them, had been insane ; that the insanity had appeared in them about the same age, and in the same form ; its existence in the child is rendered more probable, and is believed upon less perfect evidence.
The transmission of this predisposition to insanity is matter of general observation, and is recognized by the best medical authorities. Esquirol says this hereditary taint is the most common of all the causes to which insanity can be referred. Esquirol on Mental Maladies, translated by Hunt, 49. See also *821 Beck’s Med. Jur. (10th ed.) 725; Taylor’s Med. Jur. (Eng. ed.) 629; Bay’s Med. Jur. § 72; Combe on Mental Derangement, (Amer. ed.) 96, who says, that authors who differ on all other points agree in this. See also Frere v. Peacocke, 3 Curt. Eccl. 664.
3. The evidence of the declarations of Scott, the deceased subscribing witness to the will, was rightly excluded. The fact that he attested the will as a witness does not, we think, furnish evidence of any opinion he had as to the sanity of the testator. He may have had no opinion on tne subject. He may have attested the will with the full belief that the testator was insane, and with the view of testifying to that opinion whenever the will should be offered for probate. No inference as to his opinion can be drawn from the mere fact of signing; and therefore evidence of a contradictory opinion expressed by him was inadmissible. The instruction of the presiding judge on this point, cannot, we think, be sustained.
4. The witness Webster having testified to facts, as to the conduct and appearance of the testator in November, tending to show insanity, also testified, we suppose on cross-examination, that he made a bond for a deed from the testator to one Hutch-ins ; that he at first refused to make the bond, but after a conversation with Hutchins, aside from the testator, concluded to do so. The effect of this fact was doubtless to control the evidence before given; practically, and in the most forcible way, to contradict him. He should therefore have been permitted to state the reasons which induced him to make the bond, and thus to show that the apparent inconsistency in his conduct was not real; that the object and purpose of himself and the obligee, in the making of the bond, were consistent with their belief in his legal incapacity to convey his estate. It was not conversation with other third parties. It was strictly part of the res gesta, giving character to the act done, by showing with what motives and for what purposes it was done.
5. The appellee, the person named in the will as executor, was clearly competent as a witness after his release of the costs. St. 1839, c. 107, % 2. The statutes passed since the trial have *83made him a competent witness, on another trial, without, such release. Sts. 1856, c. 188; 1857, c. 305.
6. A majority of the court think the instruction to the jury, that the legal presumption, in the absence of evidence to the contrary, was in favor of the sanity of the testator, was correct. We all agree that it does not change the burden of proof, and that this always rests upon those seeking the probate of the will. See Crowninshield v. Crowninshield, 2 Gray, 532. The opinion in that case expresses my own view as to the existence of the legal presumption. ° Exceptions sustained.