In 1972, Friðfinnsson placed a handwritten advertisement in Fandangos, a magazine conceived by artist Raul Marroquin and developed at the Jan van Eyck Academie in Maastricht, inviting readers to send him their personal secrets. The announcement read: I collect personal secrets! Please send yours to me, I am looking forward to learn them and I will keep them carefully. The limited circulation of the underground publication meant almost no responses arrived. The advertisement was repeated in a third issue in 1974, again to little effect.

More than thirty years later, in 2007, the advertisement was republished in Point d'Ironie, the magazine run by Hans Ulrich Obrist and Agnès b., this time with the words. This time, letters arrived. The sealed secrets were stored in a bank vault.

In 2015, curator Krist Gruijthuijsen invited Friðfinnsson to bring the project to its conclusion at Kunstverein Amsterdam. As Friðfinnsson himself noted: contrary to what the advertisement said, the secrets were never opened or learned. The accumulated secrets were shredded and bound with bookbinding glue into a monochromatic square plate, mounted between two iron poles and visible from both sides. The exhibition presented the completed work alongside the original advertisements, making visible the full arc of a project that had unfolded across four decades. With its completion in 2015, the work's title changed from I Collect Personal Secrets to I Collected Personal Secrets