The Cosmic Lifeguard and other stories

My seventeen short stories are arranged in chronological order with the exception of the first "The Cosmic Lifeguard" which is the story of an alien who can recover victims from a watery grave. As for the rest, they start in ancient Greece and finish with a story of the very distant future. Many of my stories started as thought experiments such as "Could someone sometime in the Middle Ages have discovered the cause of bubonic plague and why were they ignored?" or "Could druids have known how to treat cancer?".