I have spent a lot of time searching for this line from Eric Schmidt:

Life is short -- you should spend time working with people you enjoy.

Or as Marc Hedlund put it, Work only with people you like and believe in.

I have my own rephrasing of this that I like:

The older I get, the more I think all that matters is working with people you like.

Is there a difference between "people you enjoy" and "people you enjoy working with"?

Definitely. I can enjoy the company of someone but not feel pushed or inspired by him or her.

Personally, I think it's less about working with people you simply like, and more about working with people that make you a better person in some way. Hopefully, you like people that make you a better person.

Make you better in terms of your value system? Make you better in terms of your knowledge?

Or both?

I think both! But, it's probably up to the individual to define how s/he wants to grow.

I choose value system over knowledge since knowledge tends to disappear over time but values get stronger over time.

But, we should also to explore the unknown to make use of the limited resources....

Explore the unknown with someone whose company we enjoy.

That way we can do both!

How about getting to know the unknown and turn them into people we like....

Working with friends is key to health and career success.

I like "getting to know the unknown and turn them into people we like".

I'd rather a stranger be a friend I haven't met yet, than be an enemy I haven't met yet!

Before we become friends, we were once strangers, so turn our peers into friends and iron out differences so we can enjoy working with one another.

You make a great point.

If a person follows the policy of "don't talk to strangers" that person will not make new friends.

The possibility of a new friend is worth taking a chance on.