A sacrament is a sensible sign, instituted by Jesus Christ, by which invisible grace and inward sanctification are communicated to the soul. The Sacraments category includes books on each of the seven holy sacraments (or mysteries) of the Church. There are books focused on a single sacrament and general books covering all seven sacraments. Some of the books are introductory or practical guides. Other books delve deep into Sacramental theology and the history and development of sacraments within the Church.