It often helps to a clearer apprehension of a position if we endeavour to conceive its opposite. We have seen Cobbett as an opponent of vaccination: let us try to think of him as its advocate. Suppose he had joined with the polite and educated mob in hailing Jenner as the saviour of mankind from smallpox, and assured the readers of the _Register_ that they would be secure from the disease for ever if inoculated with cowpox--an easy and harmless operation. Then after a while imagine him reporting that he had been misled--that the operation was not so easy as represented, nor always so harmless. By and bye he would be the bearer of a more serious revelation. Some of the vaccinated, warranted secure, had taken smallpox, but such misadventures, he would explain, were due to the use of a wrong sort of cowpox, of which there was a spurious variety. But the suggestion of spurious cowpox creating alarm and discouragement of vaccination, it would be necessary for him to counteract the declaration with the avowal that by spurious cowpox was not meant spurious cowpox, but simply irregularities in the action of the genuine virus on the arms of the vaccinated. But even these excuses would be insufficient. It was not difficult to ascribe smallpox after vaccination to careless practice, or to virus that was not the right sort of cowpox; but when smallpox was found to occur in numerous instances after Jenner’s own vaccinations and those of the most accomplished practitioners, What was to be said? Why, what was said, that when vaccination did not prevent smallpox, it made it milder! Imagine, if we can, Cobbett’s honest and vigorous intelligence retreating through this slush of apology and prevarication! Yet through such slush every follower of Jenner had to trudge.