Origin in 1400, " a book that lies permanently in some specified place" (especially a large copy of a breviary in a church), noun from leggen "to place, lay" (see lay (v.)). Perhaps formed on the model of a Dutch word; the -er seems to indicate "that which has been." Commercial sense of "book of accounts" is first attested 1580s, short for ledger-book (1550s). Ledgers have been around for over six hundred years, changing from a book written by the first business people to an encrypted database in the form of blocks. At least a digital ledger of blocks is the objective to inject more trust into the supply chain. The encrypted ledger is the first step in the blockchain. The ledger of the future is shared among all participants in the transaction with no sole ownership. Can you imagine a captain of a ship hundreds of years ago sharing a ledger of his travels? A ship captain giving away this secrets? The new ledger is automated trust. Hold on tightly.
Distribute the chain, automate the handwriting, encrypt the treasure