What effect does the veil have on ministers appearance, according to the village physician?

From the text:

"Something must surely be amiss with Mr. Hooper's intellects," observed her husband, the physician of the village. "But the strangest part of the affair is the effect of this vagary, even on a sober-minded man like myself. The black veil, though it covers only our pastor's face, throws its influence over his whole person, and makes him ghostlike from head to foot. Do you not feel it so?"