That had nothing to do with Mr. Thornton; she never dreamed that he, or any one else, could find cause for suspicion in what was so natural as her accompanying her brother; but what was really false and wrong was known to him, and he had a right to judge her. 
She never dreamed that Mr. Thornton, or anyone, might find cause for suspicion in her accompanying her brother. It was the lie that shamed her. Her false, wrong act was known to him, and he had a right to judge her.
