The greatest safeguard is, that upon the trial of a question of fact both sides are represented by counsel, and the opportunity which cross-examination offers to an advocate of even reasonable and ordinary skill is such, that these conclusions and inferences may be sifted down through the chain of observation, and the process of drawing these conclusions and inferences from a series of facts, tested in such a manner that the improbability, probability, or truth of any given inference or conclusion may be determined with substantial accuracy. The illustrations which have been given above exhibit the simplest form in which so-called direct testimony can be demonstrated to be not always positive and direct testimony, but somewhat a matter of inference. Other examples and illustrations of common occurrence will exhibit still more closely the line between actuality and opinion. At times it becomes essential to the determination of a question, that the courts should know whether or not a person was angry, whether or not he was intoxicated, or whether or not at a given time, when his mental status was under observation, he acted rationally or irrationally. Lay witnesses have for many years been permitted to testify from observation, and without possessing any special qualification to do so, as to the existence or non-existence of such conditions as those just mentioned in a person whose actions are under consideration. It is manifest that in making any such inferences the witnesses’ testimony is mainly a conclusion based on inference. Take the case of anger. How shall that be determined? It is difficult to describe anger. A loud voice, a flushed face, the use of bitter words, nervous, excitable, demonstrative action—all these symptoms might occur, or but few of them might occur. So, too, in the matter of intoxication. It is well known that some individuals exhibit the effects of intoxicants in an entirely different manner and degree from others. Some men who are very much intoxicated, so as to be quite incapable, in the eye of the law, of forming a criminal intent, or of contracting an obligation which would be valid, may still be able to walk perfectly straight, or to talk without much confusion. Others, whose walk and demeanor would indicate a considerable degree of intoxication, might be mentally clear and unruffled and even stimulated by intoxicants to precise mental co-ordination and reasoning. Again, there are persons, as to whom a witness, after stating that he had observed them, and after stating the particular matters and things in which such persons were engaged, might with apparent accuracy state that they acted rationally or irrationally, and yet such persons might nevertheless, upon further examination, be found to have been acting according to a particular custom or habit, or idiosyncrasy of long years’ standing. Thus it is apparent that in each of these cases, when the witness attempts to state what, out of necessity, the court