We recently asked the leaders of two idea-driven companies what was the most important characteristic they looked for when hiring or promoting managers. Their surprising answer: Humility.

Inditex, best known for its Zara brand of “fast-fashion” stores, is headquartered in A Coruna, Spain, and is the world’s largest clothing company with over 6,000 stores in 70 countries. Zara’s business model is built around closely listening to customers and rapidly acting on the resulting information. It rel...