In May 2020, the publication of a scientific paper on the rejuvenation of rats shook the foundations of the community that studies the possibility of undoing aging. An average epigenetic rejuvenation of 54% of the animals was reported in the article, in addition to the reversal of dozens of biochemical markers of old rats to values typical of young rats. The main developer of the treatment that led to these results was Dr. Harold Katcher, author of The Illusion of Knowledge. The reception of the specialized scientific community to the experiment was shock, with the phrase "it's too good to be true" repeated almost instinctively. Thus, Dr. Katcher decided to write this book, explaining in detail the foundations of his theory of aging and the evolutionary and biochemical bases of the mechanisms that determine the lifespan of different species. However, in this book, Dr. Katcher has done much more than address the strictly scientific part. By also conducting an in-depth analysis of the history of scientific ideas and humanity's relationship with the idea of immortality, he shows that it is no accident that he may have made the greatest discovery in human history.