It offended him both as a lawyer and as a lover of the sane and customary sides of life, to whom the fanciful was the immodest. And hitherto it was his ignorance of Mr. Hyde that had swelled his indignation; now, by a sudden turn, it was his knowledge.
FORM: explicit, The meaning of this statement is explicitly telling the readers Mr. Utterson's feelings and why he feels that way. He's offended and it's due to his ignorance of Mr. Hyde. This section tells us exactly Mr. Utterson's feelings within the context of the story as a whole at the moment.