As we have taken diarrhea and pneumonia down, even malaria down quite a bit, the portion of the days that are very early in that 5 years - the first month, the first day - it's about half now. Yet that's the part we understand the least.

In programming when you're making a change you have to know all the affected places, and you have to be able to model in your head what the performance impact will be.

It's hard to improve public education - that's clear.

The inventory, the value of my company, walks out the door every evening.

When you write a piece of software you assume a certain type of hardware. If you assume hardware that's too powerful then you can't sell many copies cause very few people have that machine. If you assume hardware that's too simple your product can't do as much.

(On being the world's richest man) I wish I wasn't ... There's nothing good that comes out of that. You get more visibility as a result of it.

When I was in my 40s, Microsoft was my primary activity.