After the Moon, space, the Internet, nanotechnologies, quantum computing, cryptos and artificial intelligence, one question arises: what is left to discover for Man? Myriads of things, of course. But there is one that fascinates as much as it frightens: the brain. At a time when Elon Musk and Sam Altman are injecting millions into neural interfaces, the boundary between human and machine becomes more porous. And in this race to fusion, the stakes go far beyond science fiction.