In late 1981, I was 23 and decided to leave Apple for Microsoft. Both were tiny. I got the protest call from Steve Jobs, which involved plenty of yelling. He tried to convince me Microsoft was about to go bust.
I was never keen about being termed 'the de facto Number Three' at Microsoft 'that nobody had ever heard of'. Neither was I enthused about people calling Office 'the dead cash cow'. When Steve [Ballmer] and Bill asked me to go in and reinvigorate it, I doubled its size in seven years to $17bn and 750 million people use it.
Don't think of me as a Father Christmas with a $36bn sack. It's not how we work. We use a clear sense of strategy to maximise our impact. We are a catalyst, not a handout. We make evidence-based investment.
Melinda Gates is my best collaborative partner. The impact of the foundation over the next few decades will be phenomenal - in beating malaria and polio, and improving agriculture.
How much money is too much? In 1986, when Microsoft went public, my wife and I calculated we were worth $3m. The impact of that money on our lives concerned us. We didn't want our children's values distorted. We believe, as does Warren Buffett, that any child should have enough money to do anything but never so much they could do nothing.
My wife and I have set up the Raikes Foundation, endowed with $100m. Of what we own, 90% will be used for philanthropy.
There is a lot of bad philanthropy. It is harder to give money away than to make it. You have to be far cleverer to make it work.