But since the facts were not available or adequate to answer the question, he turned to an examination of the causes of mental illness to see "whether the causes are more or less abundant, and act with more or less efficiency now than formerly, and are likely to produce more or less lunacy.”Since the causes derived from mental over-exertion, insecurity, social maladjustments, and the like, Jarvis was able to support his belief. Thus, he concluded: