Ordinarily, a person proved to have been insane at any time is presumed to remain so until the contrary is proved, though this is not always so. If this is held to be the law, there could be no doubt of the propriety of proving the witness's insane delusion before the time in question; but if it were not so, and if such was not held to be the presumption, still I think evidence of the witness's insane delusion at a time prior to the period in question would have some tendency to prove his insanity at that time, and the evidence, therefore, should have been admitted.