Nowadays, as much as in the time of Socrates, a great many of the difficulties in our advancement toward truth are due to errors of conception. By the teachings of this man a school of philosophers arose—the dialecticians, who spent their lives in discussions and considerations, aiming at the most exact definitions of words and the limitations of concepts.
Neglect of exactness in defining just what is meant by certain terms in pathology renders infirm many of the statistics quoted in the literature of tuberculosis.
Human tuberculosis may assume so many different forms, its progress and terminations are so heterogeneous, that great difficulties may occasionally arise, when it becomes necessary to decide whether a given pathologic process belongs to tuberculosis or some other affection. For instance there was a temptation to class a peptic ulcer of the stomach which was found in a case of pulmonary tuberculosis at postmortem examination