Studying the external alone, man begins to feel himself to be nothing. These vast powers of nature, these tremendous changes occurring — whole communities wiped off the face of the earth in a twinkling of time, one volcanic eruption shattering to pieces whole continents — perceiving and studying these things, man begins to feel himself weak. Therefore it is not the study of external nature that makes one strong. But there is the internal nature of man — a million times more powerful than any volcanic eruption or any law of nature — which conquers nature, triumphs over all its laws. And that alone teaches man what he is.