One of his students later recounted a time when Lister admonished an instrument clerk who had brought an uncovered tray full of knives into the operating theater. The seasoned surgeon quickly threw a towel over the tray and said in slow, sorrowful tones, “How can you have such cruel disregard for this poor woman’s feelings? Is it not enough for her to be passing through this ordeal without adding unnecessarily to her sufferings by displaying this array of naked steel?”