Elon Musk may be really, really smart, but even he can't carry out his vision alone. Like any business, Tesla needs to recruit talented people. 

Tesla especially needs artificial intelligence talent to fulfill its self-driving vehicle ambitions. Building electric vehicles is hard enough (especially ugly ones), but building vehicles with what Tesla promises will have "full self-driving capabilities" is even harder.

Which is why Musk -- who has a knack for blending practicality with promotion -- tweeted this on Sunday.

Unfortunately, having the ability to deliver breakthroughs in artificial intelligence capabilities sounds like the letters "PhD" need to appear on your resume.

Or not.

Musk doesn't care whether applicants have a college degree. He doesn't even care whether they graduated high school. 

Candidates will have to demonstrate an ability to code. They will have to demonstrate knowledge.

But educational background is irrelevant.

In short, what you know -- not how you learned it -- is what truly matters.

Why that message is attractive to candidates.

As HubSpot co-founder Dharmesh Shah says, "You aren't filling a position. You're putting the right person into a job. You need a doer of stuff that needs to get done."

If getting the right things done matters most, hire the people who can get the right things done.

That's an extremely powerful message for people on the downside of advantage. Those who didn't go to the "right" school. Those who don't have the "right" connections. Those with resumes dominated by white space. 

People who feel, given the right opportunities, they can play a part in making great things happen.

In short, underdogs. Which is exactly what Tesla positions itself to be.

"Join us," Musk might as well have said, "and together we will show all the critics, doubters, and naysayers what we are really made of."

Think that's not an attractive premise to talented people yearning for a chance?

Think again.

Why that message reinforces the Tesla culture.

Musk is a fan of hard work -- and expects employees to work just as hard.

As he's said, since Tesla competes "against massive, entrenched competitors ... (employees) must work much harder than other manufacturers to survive."

For good reason, Musk feels: To support the "mission of accelerating the advent of sustainable transport and energy, which is important for all life on Earth."

Achieving a lofty vision requires hard work, dedication, and perseverance.

In other words, doers of stuff that needs to get done.

As Musk said in reference to a "super fun" party he plans to have at his house with the Tesla artificial intelligence and autopilot team:

You can build skills. But you can't train enthusiasm. You can't train a solid work ethic. Those traits can matter as much -- and even more -- than the skills a candidate brings.

According to one study, only 11 percent of the new hires that failed in the first 18 months failed due to deficiencies in technical skills. The vast majority failed due to problems with motivation, willingness to be coached, temperament, and emotional intelligence.

Musk's tweet recognizes a fundamental leadership truth: You can train almost any skill... but it's nearly impossible to train attitude. The most valuable employees are those who possess skill, as well as dedication, teamwork... and a knack for getting things done. 

Which, by extension, means the most valuable current Tesla employees are those who are not just talented, but who possess a "hardcore work ethic, talent for building things, common sense, and trustworthiness."

Musk surely knew his tweet would make news. (Hi, Elon!) He surely knew it would be noticed within his company as well.

In this one, he hit multiple birds -- customers, investors, current employees, prospective employees -- with one message stone. Countless people were reminded that what Musk cares most about is delivering on his, and Tesla's, vision.

All while recruiting talented people who may otherwise never have applied for a job.

Can't beat that.