The prevalence of insanity as compared with other diseases at the present time may be fairly estimated from the statistics of Massachusetts for twenty years, where there were 604,677 deaths reported, including 2145 from suicide, 1995 from insanity, 1838 from delirium tremens and intemperance. The reported deaths from pulmonary consumption are fifty times as many as from insanity; from diarrhœal diseases, thirty times; from pneumonia, twenty times; from diphtheria, including croup, fifteen times; from scarlet fever, heart disease, and typhoid fever, each eleven times; from accidents, ten times; from cancer, five times; from childbirth and measles, each more than twice as many. The average death-rates reported from insanity per 100,000 inhabitants were 6.24 from 1861-70, and 7.12 from 1871-80, whereas the increase in the number of admissions to Massachusetts insane asylums in the twenty years was from 846 to 1610. The total number of insane people living in the State is less than the number of consumptives dying each year, and far less than the number of syphilitics. CAUSATION.—It is clear that only a small proportion of the human race is liable to become insane, and one can only wonder that so few brains are overthrown by the multiplicity of causes in modern life which tend to disturb those “invisible thoroughfares of the mind which are the first lurking-places of anguish, mania, and crime.” When we come to investigate the causes of mental disease, we find that they are of two kinds—remote or predisposing and immediate or exciting. They are also moral or mental and physical.