Sentence:  He had never felt a pain or a sorrow, and did not know what they were, in any really informing way. He had no knowledge of them except theoretically—that is to say, intellectually. And of course that is no good. One can never get any but a loose and <WSD>ignorant</WSD> notion of such things except by experience. 
Meaning of the word marked with <WSD> tags:  Resulting from ignorance; foolish; silly.