instead of in its usual wide differences of mutu throughout the whole er ven than in the case of of liberal rather than d 1. And since human to leave something to ords themselves, howeve ecision, however great, only safeguard against usion rests in a liberal

sudor est," is the significant language of the great teacher of oratory.

And there should be a corresponding degree of earnestness on the part of experts to throw light upon those difficult problems which they are specially called to expound. Their position also involves the dignity of their profession, as well as their own personal reputation, for they are truly advisers of the court, amici curia, rather than parties interested in the issue of the trial. This fact, it is painful to confess, is too much ignored both by counsel as well as courts, and the expert is constantly apt to be treated like an interested party, whose every word is tainted with the prejudice of a personal concern in the transaction. It would be better, were it possible, for the court alone to examine experts upon those points on which their professional opinions are needed, rather than to hand them over to counsel, each of whom has an interest in making their testimony aid his own side, and to that extent forcibly impressing upon it a unilateral character. But since this can not be, under existing modes of administering justice, the next best thing is to define accurately the authority, limits, and characteristics of skilled testimony.

and wisely said, that " Iman is the trust of givi y always be assumed : ven for the purpose of ir ers. It is not alone the nsel; physicians also, i skill, may, and often de and their responsibly hat counsel is administered rather than of spontaneous forming the evidence i this ndation. It is upon ined, and it is no wonde nce is attached to securing mulative facts connecting ed, with the allegation a g these things, we shal eal in keeping its links pelling attempts to breas patronis circa testim

ounsel.”

§ 105. As all definite knowledge springs from the possession of facts corroborating previous conjectures, so evidence is the expression of a necessity of the human mind for all such facts as will enable it to form a conclusive judgment. Without evidence, therefore, there can be no knowledge, and in order to secure it the law seeks for testimony either through the mouths of living

"L'esprit ne sait veritablement que ce qu'il voit avec évidence." Male branche, Recherche de la Vérité, Liv. 13, c. 4.

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witnesses, the agency of written instruments, material objects, and surrounding circumstances, or expressions of opinion predicated upon an acknowledged state of facts. These classifications, so far as they relate to human testimony, prepare us to see that all witnesses may be divided into two categories, viz., that of ordinary and that of skilled witnesses, or experts. The first category includes all persons competent to testify to any fact of which they have personal knowledge; the second defines such only as are skilled (periti) in some special science or art. As a general principle in the law of evidence, a witness is called for the express purpose of testifying to a fact within his own knowledge, and which fact must have come to him. through personal observation, and not through hearsay. The former constitutes direct and absolute testimony, the latter only indirect, uncertain, and consequently unreliable testimony. The Roman law very appropriately stigmatizes it as testimonium caecum, and at common law it is universally rejected, except in matters of public opinion touching reputation.

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In a treatise like this, restricted to medical evidence alone, it will be unnecessary to discuss the law of evidence as applicable to ordinary witnesses, for physicians, when summoned to act as such, stand on the same footing as all other persons. It is different, however, when they appear as experts, since the character and the value of their testimony is thereby entirely changed, the rules governing such testimony being framed to meet a new and exceptional state of things. And at the outset, it may be said that opinions, in general, are not evidence, for they are in plain and palpable violation of the germinal principle of all evidence, which is personal knowledge directly acquired. They are then either someth ng more or something less.

written instruments, materi ircumstances, or expressions n acknowledged state of fac r as they relate to human test at all witnesses may be divi that of ordinary and that i ts. The first category include estify to any fact of which the the second defines such only e special science or art. Ast of evidence, a witness is cal of testifying to a fact within h fact must have come to tion, and not through hears rect and absolute testimony, ain, and consequently unrelis law very appropriately stigm cum, and at common law it! pt in matters of public optic

facts. But on questions of science or trade, or others of the same kind, persons of skill may speak not only as to facts, but they are allowed also to give their opinions in evidence. The opinion of medical men is evidence as to the state of a patient whom they have seen. Even in cases where they have not themselves seen the patient, but have heard the symptoms and particulars of his state, detailed by other witnesses at the trial, their opinion on the nature of such symptoms has been properly admitted." While thus departing from the strict principles of evidence based upon facts personally observed by the witness, the law confines such testimony strictly to such matters as pertain to science, and are not of general knowledge.1 And any witness offered as an expert who can not establish the fact of special skill in the particular department which he is called upon to illuminate, will be rejected.2 For it is a principle always to be regarded in such cases that general knowledge belongs to the character of an ordinary witness, and contrariwise, special knowledge is the distinguishing qualification of an expert. And the

1 Gibson v. Williams, 4 Wend. 320; Morse v. State. 6 Conn. 9; Peterboro v. Jaffrey, 6 N. H. 462; Rochester v. Chester, 3 N. H. 349; People v. Bodine, 1 Denio, 281; Swan v. O'Fallon, 7 Miss. 231; Woodburn v. Farmers' and Mechanics' Bank, 5 Watts & Serg. 447; Rider v. Ocean Ins. Co. 20 Pick. 259; Harger v. Edmonds, 4 Barb. 256; Giles v. O'Toole, 4 Barb. 261; Robertson v. Stark, 15 N. H. 109; Concord R. R. v. Greeley, 3 Foster, (N. H.) 237; Woodin v. People, 1 Parker, Cr. R. 464; Cook v. State, 4 Zabrisk. 843; Patterson v. Colebrook, 9 Foster (N. H.) 94; Spear v. Richardson, 34 (N. H.) 428; Wagner v. Jacoby, 26 Miss. 530; Mobile Marine Dock and Mut. Ins. Co. v. McMillan, 31 Alab. 711.

2 Boies v. McAllister, 3 Fairf. 308; Lester v. Pittsford, 7 Vermt. 161; U. S. v. Willard, Paine, 539; McLean v. State, 16 Alab. 672; Luning v. State, 1 Chand. (Wis.) 178; Daniels v. Mosher, 2 Mich. 183; Comm. v. Wilson, 1 Gray, 337; Dorsey v. Warfield, 7 Md. 65; Winans v. N. Y. & Erie R. R. Co. 21 Howard, U. S. 88; Winter v. Burt, 31 Alab. 33; Harris v. Panama R. R. Co. 3 Bosw. (N. Y.) 7; Sinclair v. Roush, 14 Ind. 450.