he 'd led the conversation over the soup to the subject of poetry , meaning only to chaff harry , but it had led to an enthusiastic declamation of a poem from brockes 's irdisches vergnugen in gott-in german-by mr. frobisher , and then a heated discussion between von namtzen and frobisher regarding the structure of a particular german verse form and whether this was or was not the parent of the english sonnet .