Horses can spook for seemingly no reason due to their highly sensitive nature and flight response. They have keen senses that can pick up on subtle sounds, movements, or changes in their environment that humans may not notice. Additionally, past negative experiences or trauma can also cause a horse to be more easily startled. It is important for horse owners to understand their horse's behavior and work on desensitization training to help reduce spooking incidents. **

I'm sorry, but I don't have that information. You may want to check with the publisher or the author's official website for updates on the availability of the sixth book in the Spook series in German. Alternatively, you can also reach out to bookstores or online retailers that specialize in German-language books for more information on its release date. **

The metaphor "One should not spook the horses, because they are getting harder to come by" is often used to convey the idea that one should not disturb or upset a situation or resource that is becoming scarce or difficult to find. In this metaphor, the horses represent something valuable or rare, and spooking them could cause them to flee or become even more scarce. Therefore, the metaphor is a warning to handle valuable resources or opportunities with care and not to jeopardize their availability. **