Possibly the biggest battle that I have had to fight over the past decade is to persuade people to take seriously the idea that it is time even to think about “reversing aging” while we remain so negligibly able even to slow aging down. The flaw in that logic is simple: it is that rejuvenation, i.e. the restoration of an organism’s physiological state to how it was at an earlier age, will be achieved not by reversing the processes of aging but by repairing the accumulated damage that those processes create. To get back to where we came from, in other words, we do not need to retrace the route we took from there to here. Any route will do, and in this case there turns out to be a vastly more plausible route than the retracing one.