Original: A book described as The Merchants Mirrour, or directions for the perfect ordering and keeping of his accounts formed by way of Debtor and Creditor, after the (so termed) Italian manner, by Richard Dafforne, accountant, published in 1635, contains many references to early books on the science of accountancy.
Simplified: There was another book written in 1635 that was described as The Merchants Mirrour, or directions for the perfect ordering and keeping of his accounts formed by way of Debitor and Creditor.