chairman of the board

In the late 1700's, many houses consisted of a large room with only one
chair. Chairs were very expensive and not everyone could have one.
Commonly, a long wide board folded down from the wall, and was used
for dining. The 'head of the household' always sat in the chair while
everyone else ate sitting on the floor. Occasionally a guest, who was
usually a man, would be invited to sit in this chair during a meal. To sit
in the chair meant you were important and in charge. They called the one
sitting in the chair the 'chair man.' Today in business, we use the
expression or title 'Chairman' or 'Chairman of the Board.'