Managers versus Leaders

The Arts and Sciences have been part of Academia from its inception. Management is a fairly new phenomenon. It started at the beginning of the 20thcentury when the Industrial Age created the formation of large complex organizations. Leadership, however, has been around thousands of years. We see that one of the functions of management is leading. It would appear that management and leadership are somehow connected, yet different.

What is the relationship between the two? Are all managers leaders? Are all leaders managers?