France Livres De Raison (Family Account Books)

Definition
A livre de raison (from the Latin liber rationis or liber rationum, that is to say "book of accounts") is a register of domestic accounting also including family or local notations. Held by the father, it was a reminder for the author, but it was primarily intended to inform his heirs. Frequently, the same livre de raison was transmitted from generation to generation, each head of family holding it in turn. Wikipedia

Content
"Apart from more or less well-kept or detailed accounts, the content of a book of reason can be extremely varied. It can be found all that is of interest to the editor: managing the family patrimony (purchases, sales, loans or loans, construction, etc.); genealogies; scoring of family events (births, marriages, deaths, which sometimes give rise to reflections or the expression of intimate feelings); meteorology and local natural disasters; relationship of travel, near or far made by the editor; echo of political events affecting the whole kingdom. Everything about health often plays an important role: details of illnesses affecting family members, recipes for medicines, prayers to holy healers ..." "These books were essentially family account books, usually of farms or businesses, but sometimes of shops. Often, they span centuries and can contain an extraordinary amount of detail, including:
 * Running accounts
 * Copies of bills paid for all sorts of items or services, including veterinaries
 * Copies of wills
 * Copies of baptism, birth, marriage, death and burial registrations
 * Lists of heirs
 * Maps of lands
 * Property ownership histories
 * Notes on local events and/or catastrophes
 * Pages from almanacs"

Deeper Research via Family Chronicles - Livres de Raison, The French Genealogy Blog

Accessing the Records
Some have been put online by Gallica, either as original manuscripts or published studies. (Click on Recherche avancée, type in the titre field "livre de raison" with the quotes, in Type de document click only manuscrit and monographie.)

The Archives nationales have published a comprehensive list of those held in Departmental Archives and in libraries throughout France here. Others have been microfilmed or have surfaced more recently, so check the online finding aids of the Archives nationales, SIV, as well.