After regaining his health , he wrote and directed Persona before returning to his earlier script which he re-wrote and filmed under the title Hour of the Wolf .
Due to a severe case of pneumonia , Bergman had to interrupt his work on the project .
After regaining Bergman 's health , Bergman wrote and directed Persona before returning to his earlier script which he re-wrote and filmed under the title Hour of the Wolf .
Due to a severe case of pneumonia , Bergman had to interrupt his work on the project .