Sentence:  On the following day my friend's exhaustion had become so great that I began to fear his intelligence altogether broken up. But toward evening he briefly rallied, to <WSD>maunder</WSD> about many things, confounding in a sinister jumble the memories of the past weeks and those of bygone years. 
Meaning of the word marked with <WSD> tags:  To speak in a disorganized or desultory manner; to babble or prattle.