Sentence:  “I don't mean all of your friends—only a small proportion—which, however, connects your circle with that deadly, idle, brainless bunch—the insolent chatterers at the opera,nb..., the neurotic victims of <WSD>mental</WSD> cirrhosis, the jewelled animals whose moral code is the code of the barnyard—!" 
Meaning of the word marked with <WSD> tags:  Of or relating to the mind or an intellectual process.