recorded in these subsidiary books, and afterwards classified therefrom
into the ledger, the names _books of entry_ or _books of first entry_
are often employed. Subsidiary books which do not form the basis of
subsequent entries into the ledger, but are merely used for statistical
purposes, are known as _statistical_ or _auxiliary books_. In the early
days of book-keeping the ledger comprised merely those accounts which it
was thought desirable to keep accessible, and was not a complete record
of all transactions. Thus in many instances records were only kept of
transactions with other business houses, known as _personal accounts_.
In the earliest examples transactions tending to reduce indebtedness
were recorded in order of date, as they occurred underneath transactions
recording the creation of the indebtedness; and the amount of the
reduction was subtracted from the sum of the indebtedness up to that
date. This method was found to be inconvenient, and the next step was to
keep one account of the transactions recording the creation of
indebtedness and another account (called the _contra account_) of those
transactions reducing or extinguishing it. For convenience these two
accounts were kept on opposite sides of the ledger, and thus was evolved
the _Dr._ and _Cr._ account as at present in general use:--

_Dr._ A.B. Contra. _Cr._
-------+-------------+---------++-------+------------+---------
Date. | Narrative. | Amount. || Date. | Narrative. | Amount.
-------+-------------+---------++-------+------------+---------
| | L s. d. || | | L s. d.
| | || | |
| | || | |
| | || | |

In this form of account all transactions creating indebtedness due from
the person named therein to the business--that is to say, all benefits
received by that person from the buisness--are recorded upon the
left-hand, or _Dr._ side, and _per contra_ all transactions representing
benefits imparted by him, giving rise to a liability on the part of the
business, are recorded upon the _Cr._ side. The account may run on
indefinitely, but as a matter of convenience is usually ruled off each
time all indebtedness is extinguished, and also at certain periodical
intervals, so that the state of the account may then be readily
apparent.