The kingdom of heaven is like leaven which a woman took and hid in three measures of meal, till it was all leavened. —Matthew 13:33 How can we be part of the kingdom of heaven here and now and spread it to others, like leaven causing a lump of dough to rise and expand? Just look at the lives of the saints. Over the past two millennia, the Church has recognized thousands of men and women who have loved and imitated Christ so wholeheartedly that they transformed the world around them—as they were transformed themselves. The saints have come from every background, people, and era. They have been rich and poor, healthy and sick, single and married, members of the clergy and of the laity. The Leaven of the Saints groups them according to the kind of Christian witness they have given the world—as martyrs, Fathers and Doctors of the Church, priests and religious, popes and bishops, national heroes, founders of religious orders, married persons, and more. The vastness of this work reveals an important truth: that each saint is a unique individual with a unique mission to grow in the knowledge and love of Christ and to make him better known and loved in the world.