[burnafter182]

As a sort of logical aside:

Split tallies were used, effectively a lock and key mechanism of receipt. A stick was marked with a contract and broken in two. If you've ever broken a piece of wood, you'll know the roughness it embodies is remarkable, and on top of that the wood itself is intrinsically patterned and readily identifiable by even cursory examination. Thus it was virtually impossible to replicate. As to how these things were enforced, I do not know. Paper contracts also leveraged this model of receipt validation for some time.