In the spring of 1844, he caught pneumonia and had to stay at home for a fortnight. While recovering, he insisted on taking part in the national celebrations that year, and his sister Camilla met him, "pale as death, but in the spirit of 17 May" on his way to the revels. Soon after, his illness returned, and now he had symptoms of tuberculosis as well. He had to stay inside, and the illness turned out to be terminal. There have been many theories about the nature of his sickness. There are some who claim he developed lung cancer after a lifetime of smoking. At the time, the dangers of smoking were unknown to most people.