Lots of people want a second act. Very few people actually get it.

What do you think of when you think of Bill Gates?

Maybe it's that he was the co-founder and original driving force behind Microsoft.

Maybe it's that he's one of the wealthiest people on the planet.

Maybe it's that he's among the most devoted philanthropists in modern history.

Here's an idea, though: You could say there are actually two versions of Gates.

He's the rare person who has had the chance to live two entirely different lives--either of which would have been enough for most people to think of him as an icon.

It's a gift, really. It's also the result of a crucial decision he made exactly 20 years ago--a milestone it seems almost nobody has even noticed. And one that entrepreneurs at any scale might want to pay attention to.

Then and now

First, the two versions of Bill Gates. Let's start with Gates version 1.0.

This is the young Gates--the entrepreneur who left Harvard, launched Microsoft, and built one of history's most successful companies, the Gates the world knew from when it first heard his name, through the end of the 20th century.

It's Gates, the obsessive taskmaster, the CEO who never took vacations, and who literally memorized his employees' license plates so he could know who was dedicated enough to work weekends (and who wasn't).

But now, there's Gates version 2.0.  

How do you square the two versions? Partly, this is the natural growth and evolution of any thinking human being over a lifetime.

But it's also the result of what Gates decided in January 2000.

Giving back to the world

Within weeks of each other, Gates actually did two related things that shaped his next 20 years (and his likely legacy):

A lot of successful people say they hope at some point to change gears and "give back to the world." But many of the biggest icons never actually do it.

Some simply run out of time. (Example: Steve Jobs.) 

Others never quite move on. (Example: Warren Buffett. He started the giving pledge with Gates, but he's still running Berkshire Hathaway.)

Others: well, the jury is still out. (Jeff Bezos has been CEO of Amazon for 26 years. Will he keep going forever? Gates was CEO at Microsoft and its predecessors for 24 years.)

We could go on. Yes, some of these other oft-mentioned icons do other things (or did other things) besides building and running their conglomerates.

But still, they kept at it: building the same entity, doing more or less the same thing. Dedicating their lives to their work.

Bigger than a Twitterversary

Gates is different. There was a time when nobody would have predicted it. 

But since stepping back from Microsoft (and especially since leaving all day-to-day work there, a few years later), he's basically dedicated his life, and his fortune, and his influence, to two things:

• self-improvement (like all those book reviews and recommendations), and
• the proposition that there is "equal value in all lives," and "to improving the quality of life for individuals around the world."

It's not something everyone would have predicted. When Gates first became a billionaire at age 31, when Microsoft went public in 1986, his mother suggested then that he turn to philanthropy.

He reportedly snapped at her: "I'm just trying to run my company!"

Now, he's almost a different person.

I admit: I started considering this idea of the two versions of Gates--and only then did I realize that it had been exactly two decades, almost to the day, since he stepped down as CEO. With few exceptions, the anniversary went unmarked.

Heck, Gates commemorated his 10th anniversary of joining Twitter the other day.

But I don't see anything on his Twitter or his Gates foundation blog about the much bigger anniversary from 20 years ago.

The decision he made then was arguably the most important decision of his entire life, and it's what made his second act possible. He's more than made the most of it.

Inc