Missions are the Church in a state of growth. They are not merely an outside activity by which external additions are made to the Church, nor are they just the geographical expansion of the Church as it is. They involve a real growth and development of the whole Church, of doctrines, practices and life, and of every individual who shares in that life. For missions are the development of the catholicity of the Church.

Catholicity is of the very nature of the Church. It is the property by which it is able to adapt itself to every human group and incorporates all genuine human values, while remaining one and transcendent. Being of the nature of the Church, it tends to realize itself as fully as possible, until the whole of humanity has been gathered up.

Until the Church has in fact incorporated every human group, and established itself in every nation, its catholicity is undeveloped, though complete as a power.