The English title of this collection is a wonderful depiction of the theme that connects the stories. It's important to notice how often the characters of the stories are away from their home, on adventures, or quests, or vacations. Then something terrible happens to the traveler, and the common thread that connects these stories is the juxtaposition of coincidence (eg. seeing a familiar face in another country) with the apparent meaninglessness of human suffering. The effect is dark and supernatural, as if something else is really going on behind the scenes.
The characters in these stories are often the victims of serious tragedy. A newlywed separated from his wife who dies randomly while they're apart. A father desperately attempting to have his dead daughter venerated by the pope. A traveler who goes to Rome for a blessing but instead sees incredible suffering and death. A woman unfairly abandoned, betrayed and committed to a mental asylum without cause.
All these stories are so vividly sad and human. The meaning of such stories comes in the small glimpses of coincidence that seems to suggest that the universe is not capricious and random, but rather that human suffering is part of a master plan somehow, but maybe not a master plan that humans would be happy with. The dark tone allows for disappointment and fear, instead of giving a pithy, one-size-fits-all answer for human suffering.