Oliver Wendell Holmes, Jr., Queenan v. Oklahoma — Opinion of the Court
“ To allow less may deprive a party of important and valuable evidence that can be got at in no other way. But, on the other hand, to allow more, to let a witness who is not an expert state an opinion upon sanity which he has formed after the event, when a case has arisen and become a matter of public discussion, must be justified, if at all, on other grounds. It is unnecessary to lay down the rule that it never can be done, for instance, when the opinion clearly appears to sum up a series of impressions received at different times. ”
