And this is the reason why it is impossible in a visitation to prevent the spreading of the plague by the utmost human vigilance; viz., that it is impossible to know the infected people from the sound, or that the infected people should perfectly know themselves. I knew a man who conversed freely in London all the season of the plague in 1665, and kept about him an antidote or cordial, on purpose to take when he thought himself in any danger; and he had such a rule to know, or have warning of the danger by, as indeed I never met with before or since: how far it may be depended on, I know not. He had a wound in his leg; and whenever he came among any people that were not sound, and the infection began to affect him, he said he could know it by that signal, viz., that the wound in his leg would smart, and look pale and white: so as soon as ever he felt it smart it was time for him to withdraw, or to take care of himself, taking his drink, which he always carried about him for that purpose. Now, it seems he found his wound would smart many times when he was in company with such who thought themselves to be sound, and who appeared so to one another; but he would presently rise up, and say publicly, "Friends, here is somebody in the room that has the plague," and so would immediately break up the company. This was, indeed, a faithful monitor to all people, that the plague is not to be avoided by those that converse promiscuously in a town infected, and people have it when they know it not, and that they likewise give it to others when they know not that they have it themselves; and in this case, shutting up the well or removing the sick will not do it, unless they can go back and shut up all those that the sick had conversed with, even before they knew themselves to be sick; and none knows how far to carry that back, or where to stop, for none knows when, or where, or how, they may have received the infection, or from whom.