ONE of the earliest versions of the effect.
Two packs, red-backed and blue-backed are used, they may be borrowed since no preparation is necessary, also an opaque envelope. Show the packs face up one in each hand. Call attention to the envelope and in order to pick it up put the pack in your right hand with the other in your left, face up, on top. Hand the envelope to a spectator to examine. Take the pack back in your right hand, suppose it is the blue-backed one, allowing the top card to remain on the bottom of the other red-backed pack, the left hand at once turning that pack face down. Hand the blue pack to the spectator, take back the envelope and put it down in front of you. Fan your pack with the faces towards you, find the duplicate of the stolen blue card, put it behind the blue one and put both on top of the pack. Invite the spectator to cut his pack and you cut yours, really you make the first part of the pass, pulling out the bottom portion of the pack and dropping it on the table. Lift off the two top cards, the duplicate red and blue cards, as one, and slip them into the envelope. Take off the top card of the lower part of the spectator's cut, and put it also in the envelope, not showing its face. Slide it to the opposite end of the envelope, take out the duplicates and show them. You can repeat the trick ad lib. by noting the index of the card that remains in the envelope. Finally place the blue pack in the envelope and hand both to spectator to examine, everything is thus left clean.