"Indeed, throughout human history, the end of life has always coincided with the cessation of the heartbeat: every hero worthy of the name has died because their heart stopped beating. Literature, works of art, and old medical textbooks provide ample evidence of this. [...] With the first cardiac surgery procedures and the invention of extracorporeal circulation, it became clear that the function of the heart could be replaced by an artificial mechanism: the person continued to live without a beating heart in his chest, as long as blood continued to flow to their brain. Doctors had recorded numerous signs, and the idea that the brain played a crucial role in human life was already well established. Based on these assumptions, a debate developed at Harvard that brought together not only doctors but also lawyers, philosophers and representatives of different faiths, as the aim was to find a definition of death that took into account the ethical concerns and the context at a given point in history. Since the Harvard guidelines, death is certified when all vital brain functions have irreversibly ceased."