It is a poignant task for me to remember Sergio Colafrancesco in this international context, in part because he started his path here that allowed him to become a very well known scientist, He did so because of his magnificent talks which drew on his profound knowledge of physics. He was a great scientist and friend.

I do not want to enter in his scientific production which is largely demonstrated in his 621 published papers and thousands of citations. I prefer to remember Sergio in his many activities that I have the privilege of knowing, thanks to our long association and friendship.

I will use for this commemoration some material coming from "A meeting in honor of Sergio Colafrancesco" organized by Paolo de Bernardis and Silvia Masi on Novembre 2, 2018 at the Department of Physics of the Sapienza University of Roma with the contributions of Paolo de Bernardis and Silvia Masi, John Carter, Franco Giovannelli, and Angelo Antonelli, and from the official memorial service "A celebration of the life and work of Sergio Colafrancesco" organized in Johannesburg at Hofmeyr House of the Wits University on June 14, 2019.