If posting is from the sales book, the ledger should be placed to the right of the sales book and the slip to the right of the ledger. After the item is entered in the ledger it is posted to the slip. When the work is completed the slip is footed and compared with the footing of the sales book. If the footings agree, it is quite evident that the correct amounts have been posted to the ledger, for it is scarcely possible that an incorrect amount has been posted to the ledger and the correct amount entered on the slip. A further daily proof may be had by inserting a blank slip of paper in the ledger wherever an item is posted. At the end of the day these ledger accounts are referred to, the amounts are drawn off, and total postings compared with the totals of the checking slips from the different books. When postings are not checked daily a form should be prepared to which daily totals will be carried. Columns are provided for each book from which posted, and these are footed at the end of the month and compared with the footings of the books. If the ledger does not balance a comparison of this proof slip with the column footings of the books will show in which book the error has been made. The form of the monthly proof slip is illustrated in Fig. 19. SPECIAL ACCOUNTING FORMS =21.= Bookkeeping, if it is to fulfil its mission, must furnish a complete record of the transactions of a business. The record must show, as well, the results of each transaction or class of transactions, with respect to their bearing on the business as a whole, or on specific sections or departments of that business. From a mere record of personal debits and credits, bookkeeping has grown into a detailed history of a business. The principles of bookkeeping are the same regardless of the nature, size, or condition of a business. But different businesses require different kinds of information; vital facts in one business may be valueless in another. The success or failure of each depends upon certain elements which must be recorded in its history. It is the work of the bookkeeper to record these facts—to write the history of the business in language that will be understood by anyone who may read it. Laying out the business history is the work of the accountant. He makes an analysis of those elements which bear on the success of the business, and determines what facts, when properly recorded, will furnish the clearest and most understandable history. And when he has determined what facts should be recorded he must plan how they are to be recorded—in what form they will present the most concise history of business transactions. His work should result in a system of bookkeeping that will present the most vitally important information, with a minimum expenditure of labor.