A stove filled with burning fuel cannot help heating the surrounding atmosphere. Not all Christian Mystics reach the same height. The heated stove attracts those who are physically cold. The stove does not need words to warm those who are physically cold. The Christian Mystic cannot help radiating the divine compassion which fills his heart.
Different stoves have different heating capacities.
The true Mystic need not preach. His every act, even his silent presence, is more powerful than a sermon.