On February 4, 2014, Satya Nadella became CEO of Microsoft, the third person to hold the office in the company’s nearly 40-year history, after company co-founders Bill Gates and Steve Ballmer.

One of Nadella’s first major tasks was overseeing the completion of Microsoft’s $7.2 billion acquisition of Nokia Corp.’s mobile-device business, a transaction that had been announced in 2013.

As a relatively old company, founded on April 4, 1975, Microsoft faced many unresolved challenges when Nadella took office. One of them was the company’s culture.

What was his plan to bring the company’s soul back? What lesson can we learn from this process?