It should come as no surprise, but Tesla CEO Elon Musk has been working on the electric car for over 25 years. It’s just another of his many paradigm-shifting hobbies, the electric car. Now, a quarter century after he began his pursuit, his company is leading the electric, autonomous car development race, and he’s checked off two of his five collegiate goals.

Musk spoke with Y Combinator CEO Sam Altman on Thursday, and the interview ranged far and wide. He spoke about many of his five original goals, including artificial intelligence and getting humanity to Mars (and beyond). But early in the discussion, he reflected on his college and Ph.D. years.

“The five things that I thought about at the time in college — so quite a long time ago, 25 years ago: Making life multi-planetary, accelerating the transmission to sustainable energy, the Internet broadly speaking, and then genetics, and A.I.,” Musk said.

Electric cars, to the young Musk (born in South Africa, in 1971), seemed like the logical place to start checking things off.

Here’s the relevant transcription:

In college, I sort of thought helping with electrification of cars was how it would start out. That’s actually what I worked on as an intern, was advanced ultra-capacitors, to see if there would be a breakthrough relative to batteries for energy storage in cars. And then, when I came out to go to Stanford, that’s what I was going to be doing my grad studies on, was working on advanced energy storage technologies for electric cars. And I put that on hold to start an internet company in ‘95, because there does seem to be a time for particular technologies when they’re at a steep point in the inflection curve. And I didn’t want to do a Ph.D. at Stanford and watch it all happen. I wasn’t entirely certain that the technology I’d be working on would actually succeed. You can get a doctorate on many things that ultimately do not a have practical bearing on the world. And I really was just trying to be useful. That’s the optimization. It’s like, ‘What can I do that would actually be useful?’

It only took Musk two days at Stanford to drop out, which some people suggest was his plan all along. And, for the most part, he doesn’t think ambitious people today ought to pursue Ph.D.s. Instead, they should follow his lead, and that of other successful, visionary entrepreneurs. To do so, he said, just do some basic calculations:

Make some estimates of, whatever this thing is that you’re trying to create, what would be the utility delta compared to the current state of the art times how many people it would affect. So that’s why I think having something that makes a big difference but affects sort of a small to moderate number of people is great, as is something that makes even a small difference but affects a vast number of people.

Go forth and prosper.

Photos via Y Combinator, Getty Images / Justin Sullivan

Joe is a writer from Vermont who lives in Brooklyn. He has written for PopSci and McSweeney’s Internet Tendency and spent a year playing with words and other writers’ dreams at Tin House in Portland, Oregon.