What did Jenner do? Did he vindicate his prescription, the fruit of thirty years of incessant thought, observation and experiment? He did not. On the contrary he dropped it. He said not another word about it; and proceeded to claim Cowpox as employed by Pearson and Woodville as his discovery. In his petition to Parliament there was no mention of Horsegrease Cowpox; but Cowpox, with “its beneficial effect of rendering the persons inoculated therewith perfectly secure through life from the infection of Smallpox,” was set forth as the result of his most attentive and laborious investigation at the sacrifice of time, money, and professional advancement. We have to recollect that Jenner was inspired with what he called “the fond hope of enjoying independence,” and he was not slow to recognise, that if he stood by Horsegrease Cowpox his “fond hope” would be wrecked. The statement may seem incredible, but the fact of the transformation is manifest at large to any one who will take the trouble to compare Jenner’s _Inquiry_ of 1798 with his Petition to the House of Commons in 1802. Pearson failed to arrest the imposture. He might have said to Jenner, “Your discovery was not Cowpox: that was well known to every dairymaid in your neighbourhood. Your prescription was Horsegrease Cowpox. You condemned Cowpox, which Cowpox has nevertheless been brought into use by Woodville and me. Keep to your Horsegrease Cowpox; make what you can of it; and leave us alone.” Had Pearson taken this course, he would have fixed Jenner to his discovery, such as it was, and have clearly defined and established his own and Woodville’s service in rendering the New Inoculation practicable and popular. But he failed to draw a firm line between Woodville and himself and Jenner, and to insist that they were operating, not only with a different pox, but with a form of pox by him rejected as useless. Through this default, he enabled Jenner to intrude into a province that was not his own, and to reap where he had not sown, and gather where he had not strawed. It is to be admitted that the facts as stated were all involved in Pearson’s _Examination_, but they were _involved_, and required picking out and sharper definition to give them effect. Truth is truth, but truth to have its rightful influence has to be made plain. It is of little avail to have a good cause at law if the means are wanting to place its goodness manifest and paramount over contention to the contrary.