We find, then, that disease may be caused by neglect in childhood, by starvation or improper food, by over-work, by terror, by excitement, and by worry, amongst a thousand other causes.
And we find that disease affects the brain, and very often leads to vice, to crime, to dishonesty, falsehood, and impurity.
And disease is one part of our environment.
A wound or a shock may have a wonderful effect on the mind. A man may slip and strike his head on a stone, and may get up an idiot A gunshot wound in the neck, a sword-cut on the head, may cause madness, or may cause an injury of the brain which will quite change the injured man's moral nature.
As to the effects of such accidents on the mind there are many interesting particulars in Lombroso's book, The Man of Genius, from which I am tempted to quote some lines:
It has frequently happened that injuries to the head, and acute diseases, those frequent causes of insanity, have changed a very ordinary individual into a man of genius.... Gratry, a mediocre singer, became a great master after a beam had fractured his skull. Mabillon, almost an idiot from childhood, fell down a stone staircase at the age of twenty-six, and so badly injured his skull that it had to be trepanned; from that time he displayed the characteristics of genius.... Wallenstein was looked upon as a fool until one day he fell out of a window, and henceforward began to show remarkable ability.
Lombroso also gives many examples and proofs of the influence of weather and climate on the mind; but for these I have no room.
Now, disease, and weather, and climate, and injuries are all parts of environment.
Food
We have seen that one cause of insanity and disease, and of immorality and crime, is degeneration. And we have seen that one cause of degeneration is "insufficient or improper food."