§940
Creed › … › Paragraph 4. Christ's Faithful - Hierarchy, Laity, Consecrated Life
IN BRIEF
"The characteristic of the lay state being a life led in the midst of the world and of secular affairs, lay people are called by God to make of their apostolate, through the vigor of their Christian spirit, a leaven in the world" (AA # 2).
Source: Catechism of the Catholic Church (Vatican.va)