* THIS INTERVIEW WITH WILL FIRST APPEARED IN ‘FAST COMPANY’ *

Nostalgia is a classically effective marketing tool. “It bypasses intellect and reaches straight to the heart,” William Higham, a consumer strategist who has helped brands like the BBC and Universal Music leverage nostalgia, told me earlier this year. “It makes you feel emotional toward the brand.”

Visit Facebook’s “Say Thanks” tool, and you can automagically create a video that documents the relationship between you and a special friend—a slideshow of all of posts and photos you’ve tagged each other in on Facebook, set to an upbeat tune, and interspersed with the message, “For the good times we’ve had…And the good times ahead…Thanks for being a friend.”

How generous and considerate of the social network to help spread love during this month of gratitude!

But also, how very clever of its marketing department.

These are not private messages sent between two friends. The Say Thanks tool tags your friend in the video, which means their friends will see it, and it also posts the video to your newsfeed, where your friends will see it. Meanwhile, it reminds all of us who see it about the good times we’ve had on Facebook; that all our friendships are catalogued there; and that some of those relationships have been cultivated, explored, and deepened, surely, via Facebook messaging over the years.

Nostalgia is a classically effective marketing tool. “It bypasses intellect and reaches straight to the heart,” William Higham, a consumer strategist who has helped brands like the BBC and Universal Music leverage nostalgia, told me earlier this year. “It makes you feel emotional toward the brand.”

And Facebook has all the raw ingredients for retrospective pathos at its fingertips: your media, your friends, and your history. That, in part, is what sets it apart from younger, cooler platforms like Snapchat. Now it just needs a way to spread this very effective advertisement, and that’s where you come in.

Facebook wants you to keep using Facebook as much as possible, but if it stuck actual adverts for itself in your newsfeed, you might be so annoyed that you’d say farewell. But fake ads? Those seem to work. Last February, to celebrate its 10th anniversary, Facebook created a similar tool for making a “Look Back” video that slideshow-ized your personal history. More than 200 million people viewed the video about their lives, and more than half of those people shared them on their Timelines. So get ready for another flood of nostalgic hosannas to friendship. You won’t get annoyed at Facebook—it’s your relentless friends you’ll come to hate