most visitors mistook it at first sight for the offices of the guild of assassins , which in fact was the rather pleasant , - airy collection of buildings next door ( the assassins always had plenty of money ) ; sometimes the young fools , slaving at their rote in rooms that were always freezing , even in high summer , heard the young assassins at play over the wall and envied them , even though , of course , the number of piping voices grew noticeably fewer towards the end of term ( the assassins also believed in competitive examination ) .