Collins on Drucker

"His generosity of spirit explains much of Drucker’s immense
influence. I reflected back on his work, The Effective Executive, and
his admonition to replace the quest for success with the quest for
contribution. The critical question is not, “How can I achieve?” but
What can I contribute?

Drucker’s primary contribution is not a single idea, but rather an
entire body of work that has one gigantic advantage: nearly all of it
is essentially right."

Jim Collins