101 U.S. 99 (1880)
In 1859 Charles Selden took the steps necessary to obtain a copyright for a book entitled “Selden’s Condensed Ledger, or Bookkeeping Simplified,” whose purpose was to exhibit and explain a distinctive system of bookkeeping.1
In 1860 and 1861 he secured copyrights for additional books that contained improvements and additions to the same system.2 Following Selden’s death, the complainant, as his testator’s representative, filed a bill against Baker alleging infringement of these copyrights.3
Baker denied in his answer that Selden had authored the books, denied the infringement, and maintained that the matter was not a proper subject for copyright.4 The parties introduced proofs, exhibited the complainant’s books and those sold by the defendant before an examiner, and presented testimony from witnesses on both sides.5 The circuit court rendered a decree for the complainant, from which the defendant appealed.6
The copyrighted materials consist of an introductory essay explaining the bookkeeping system together with annexed forms or blanks made up of ruled lines and headings that illustrate the system and show its practical application.7 The system produces the same results as double-entry bookkeeping but displays the operations of a day, week, or month on a single page or on two facing pages.8 Baker employs a similar plan for achieving equivalent results, although he arranges the columns differently and uses different headings.9
The complainant’s evidence is directed principally at establishing that Baker utilizes the identical system explained and illustrated in Selden’s books.10 The central factual question presented is whether Selden, through the copyrights on his explanatory books, obtained an exclusive right to the bookkeeping system itself.11
Whether the copyright of books explaining and illustrating a system of bookkeeping confers upon the author an exclusive right to the use of that system?12
Copyright secures the exclusive right of printing and publishing the book but does not confer an exclusive right to the art or system described in it.13 The distinction between the book as such and the art which it is intended to illustrate is fundamental, and the latter can only be secured by letters-patent.14
No. Selden obtained copyrights only for books that explained and illustrated his bookkeeping system.15 Because the system itself was never patented, the copyrights protect solely the expression contained in the books and leave the underlying art open for public use.16 Baker’s employment of a similar plan with a different column arrangement therefore does not infringe any copyright.17
The copyright of books explaining and illustrating a system of bookkeeping does not confer upon the author an exclusive right to the use of that system.18
Whether blank account-books consisting of ruled lines and headings are subjects of copyright?19
No. The books claimed by the complainant consist of an introductory essay together with forms or blanks made of ruled lines and headings that illustrate the system.22 These ruled lines and headings function as necessary incidents to the art of bookkeeping and pass to the public upon publication of the explanatory books.23 Blank account-books consisting of ruled lines and headings are therefore not subjects of copyright.24
Blank account-books consisting of ruled lines and headings are not subjects of copyright.25