A fascinating journey into Slavic folklore, something I'm new to but utterly enjoyed. Each spirit has origins ranging from innocent to dark, and I love how they all have distinct personalities, some with obsessions and pet peeves (and weaknesses for those who need to fight or tame them, Supernatural-style). Despite their capacity for mischief and harm, so many of these spirits still coexist with humankind, helping and protecting them when given the proper respect. They are as human as the people who created and passed down their stories, and that's what makes them memorable.
While introducing us to these spirits, the book also provides an important glimpse into the lives of the old peasantry - their daily labors, recreation, reverence for life and death, strong family ties - things that I haven't read much about elsewhere, and that's partly why folklore is so important. It's a way of preserving the essence of a people, particularly one that doesn't usually leave behind written histories. Their beliefs speak to the resilience (and sometimes ruthlessness) of people who battled harsh conditions daily, and found explanations in the mysterious workings of nature.
On another note, I found this book useful from an aspiring writer's perspective. Developing ethnic groups for a medieval fantasy is difficult without distinct belief systems and cultural norms; knowing how those of different groups might clash or merge with each other is equally important. The myths and folktales in this book are a great illustration of such a phenomenon - not only how religious beliefs and rituals originate, but how they change over time. I was also inspired by the stories around the Rhodope sanctuaries and lost cities, some of which centered around snake worship and healing rituals. I might be the furthest thing from religious, but this was an enjoyable and informative read, and I'll definitely be checking out the others in this series.