Giorgio Parisi is an Italian theoretical physicist, whose research has focused on quantum field theory, statistical mechanics and complex systems. His best known contributions are the QCD evolution equations for parton densities, obtained with Guido Altarelli, known as the Altarelli–Parisi or DGLAP equations, the exact solution of the Sherrington–Kirkpatrick model of spin glasses, the Kardar–Parisi–Zhang equation describing dynamic scaling of growing interfaces, and the study of whirling flocks of birds. He was awarded the 2021 Nobel Prize in Physics jointly with Klaus Hasselmann and Syukuro Manabe for groundbreaking contributions to theory of complex systems, in particular "for the discovery of the interplay of disorder and fluctuations in physical systems from atomic to planetary scales". Former president of the Accademia dei Lincei and member of the American National Academy of Sciences, his scientific research has mainly concerned statistical physics, mathematical physics and condensed matter physics. However, his studies have a relevance that goes beyond these boundaries to go into other areas of knowledge, from anthropology to cognitive sciences, from finance to social sciences. Abstract: Science is very ancient. The first scientists were those who discovered fire or tamed animals. Over the centuries and millennia, science has taken on a whole new meaning. Today, therefore, it is something very different from what it was in the beginning. In this seminar I will talk about how science has evolved, what is its meaning now and what are the duties of scientists. The Joint Colloquium, the first public talk by Professor Parisi since the announcement of the award by the Royal Swedish Academy of Sciences on 5 October will take place on 22 October in the main hall of SISSA in Via Beirut, next to the campus of ICTP, in Grignano, Trieste, starting at 11.00 am. To register for the online event in Zoom, the link is: https://zoom.us/webinar/register/WN_EUsNgW53TAWWrhTtGkr81Q You will receive an email confirmation after registering. The event will also be livestreamed on the ICTP’s YouTube Channel. All are welcome to follow this special event.