After the death of St Josemarí a, his successor, Blessed Alvaro del Portillo, had an Audience with Pope St Paul VI. Referring to the teachings of the founder of Opus Dei, St Paul VI asked that all these be carefully collected " because they are now already a treasure which belongs to the whole Church" . This volume contains Letter 29, one of some 38 of a foundational nature which St Josemarí a Escrivá wrote. Although they are addressed to all members of Opus Dei, they are valuable resources for everyone in the Church. Letter 29, dated January 9, 1959, is also designated by the first words Dei amore, and is on the work of St. Gabriel. It deals with the vocation of supernumeraries: a call to personal holiness through the sanctification of their work, their married and family life. This leads, as a consequence of personal action, to illuminating temporal realities and structures with the life and light of Christ, to contributing effectively to solving the great problems of mankind.