Pope John XXIII's first encyclical, Ad Petri Cathedram, was issued eight months into his pontificate and was neither an important social document nor doctrinal exposition. Instead it looked at truth, unity and peace with distinctive familiarity and concern. The second, Sacerdotii Nostri Primordia, commemorated the 100th anniversary of the death of St. John Vianney, while Grata Recordatio considered the use of the Rosary. Princeps Pastorum, his fourth encyclical, used 1 Peter 5:4 as its biblical text and celebrated Roman Catholic missions.