Where no fear was, a book about fear

Let us divide our fears up into definite divisions, and see how it is best to deal with them. Lowest and worst of all is the shapeless and bodiless fear, which is a real disease of brain and nerves. I know no more poignant description of this than in the strange book Lavengro:

"What ails you, my child,' said a mother to her son, as he lay on a couch under the influence of the dreadful one; 'what ails you? you seem afraid!'