Two cards freely selected and signed by the spectators. The cards are openly torn into quarters. The spectators actually see the magician count the separate pieces, yet in an instant both cards are fully restored and given our for examination. Nothing added, nothing taken away. Any cards can be used and they are not prepared in any way! They can look all they want for the gaff, they won't find it...because there is none to find.
Paul Harris' Immaculate Connection was based on this Sankey idea.