“Above all, the performer must give the impression that he possesses some mysterious power over locks.” [Burling Hull, the Challenge Handcuff Act]

According to Patrick Cullington [Houdini the Key], Burling Hull added this text to the written instructions that went with Houdini’s Defiance Handcuff act when he republished them under his own name. Hull didn’t steal that idea from Houdini’s writings, he stole it from Houdini’s act.

Houdini’s “strange power over locks” was demonstrated in every performance of his handcuff act and it was definately demonstrated in his movies as evidenced by The Grim Game movie stills depicted in this blog. 

Everything about Houdini’s expression indicates that he is exercising a “power”. [Patrick Cullington, Houdini the Key]