2012 was a big year for Facebook. In April of that year, Facebook announced it would acquire Instagram. In June, it named Sheryl Sandberg to its board of directors. And in October, Facebook announced it had one billion active monthly users.

“Helping a billion people connect is amazing, humbling and by far the thing I am most proud of in my life,” CEO Mark Zuckerberg wrote then in a public post, announcing the milestone. “I am committed to working every day to make Facebook better for you, and hopefully together we will be able to connect the rest of the world too.” In another post that day, Zuckerberg wrote that he and his colleagues at Facebook “believe that the need to open up and connect is what makes us human. It’s what brings us together. It’s what brings meaning to our lives.”

A trove of internal Facebook emails released by the U.K. Parliament on Wednesday reveals what was happening inside the company at that time. Just weeks after Facebook hit its billionth active monthly user, Zuckerberg typed out an email to colleagues with his thoughts on the data access terms Facebook might want for apps operating on the platform.

“I think we should go with full reciprocity and access to app friends for no charge. Full reciprocity means that apps are required to give any user who connects to FB a prominent option to share all of their social content within that service back…to Facebook,” Zuckerberg wrote.

He went on:

We’re trying to enable people to share everything they want, and to do it on Facebook. Sometimes the best way to enable people to share something is to have a developer build a special purpose app or network for that type of content and to make that app social by having Facebook plug into it. However, that may be good for the world but it’s not good for us unless people also share back to Facebook and that content increases the value of our network.

(For the record, Facebook says the tranche of emails is “cherrypicked,” and “tells only one side of the story and omits important context.”)

In short, the reciprocity arrangement Zuckerberg was describing involved the terms Facebook sets for third-party apps built on its platform. The arrangement determines how much, and which kinds, of data Facebook requires those apps to provide in return for access to its network. In this case, apps were given access to friend lists. With data gathered through reciprocity, Facebook’s advertisers would be able to target users even better than before.

The emails reveal a core dissonance between Facebook’s marketing and how its users were leveraged in a business sense.

In another, earlier email, Zuckerberg discussed user data in a different context: how it might be obtained by another party. In an email to then-VP of product management, Sam Lessin, Zuckerberg wrote that he was skeptical about a “data leak strategic risk,” adding: “I agree there is clear risk on the advertiser side, but I haven't figured out how that connects to the rest of the platform. I think we leak info to developers, but I just can’t think if any instances where that data has leaked from developer to developer and caused a real issue for us. Do you have examples of this?”

In 2018, following the Cambridge Analytica allegations, that question now seems pretty ominous.