Warden: The patient that came in yesterday is having a fit.
Van Helsing: Which one?
Warden: The one that bit the cow.
Count Dracula: Death is not the worst. There are things more horrible than death.
Count Dracula: The absence of love is the most abject pain.
Answer: True, though the rats comment was deliberate hyperbole. Kinski suffered from mental illness much of his life. He was often volatile, erratic, disruptive, and sometimes violent on movie sets. Kinski and Herzog had a long professional collaboration but also a friendship pre-dating Herzog's directing career. Otherwise, though Herzog admired Kinski's talent, he probably would never have tolerated working with him; he is the only director who worked with him more than once. Herzog did a documentary about Kinski after his death, which included footage of his on-set rants. Clips are on YouTube.
raywest ★
Moreover, Herzog was initially reluctant to hire Kinski in Fitzcarraldo movie because he was afraid that Kinski would go "totally bonkers" if trapped in the Amazon for any length of time, and his fears proved to be well-founded.
To correct a slight factual error in the answer: Director Alfred Vohrer worked on more movies with Kinski than Herzog did.
lionhead