Stephen Johnson Field

“ If, for example, the question were as to the damages sustained by a plaintiff from a fracture of his leg by the carelessness of a defendant, the jury would ill perform their duty and probably come to a wrong conclusion, if, controlled by the testimony of the surgeons, not merely as to the injury inflicted, but as to the damages sustained, they should ignore their own knowledge and experience of the value of a sound limb. Other persons besides professional men have knowledge of the value of professional services ”

“ While they cannot act in any case upon particular facts material to its disposition resting in their private knowledge, but should be governed by the evidence adduced, they may, and to act intelligently they must, judge of the weight and force of that evidence by their own general knowledge of the subject of inquiry. ”