Comets have always been thought as relics from the early days of the solar system. ESA’s Rosetta mission by following the comet 67P/Churyumov-Gerasimenko (67P/CG) along its trajectory, delivered for the first time not just a snapshot in time of a comet nucleus but its full time dependent evolution as it approached the sun. Just like the stone that gave the name to the mission, the wealth of data recorded provides a unique opportunity to help decipher the 4.5 billion yearlong story of the solar system. It turns out that the book is not so easy to read! In this talk, I will discuss some ways to reconcile some of the puzzling aspects of 67P/CG with the recent progress made in understanding the formation of planetary systems from the study of exoplanets.