Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. God Himself is not secure, having given man dominion over His works! Avoiding danger is no safer in the long run than outright exposure. The fearful are caught as often as the bold. Faith alone defends. Life is either a daring adventure or nothing. To keep our faces toward change and behave like free spirits in the presence of fate is strength undefeatable.

Helen Keller (1880-1968) American author and lecturer

Let Us Have Faith, “Faith Fears Not” (1940)
    (Source)

Reprinted in her compilation book, The Open Door (1957). This quotation is often given in excerpted form, leaving out certain sentences, or even rearranging some of the sentences and sometimes making it seem that the two sources are actually different.