We must understand the kingdom of heaven in one sense as a kingdom in which both are included, the man who breaks what he teaches, and the man who practises it, though one is the least and the other is great in the kingdom, while in another sense it is a kingdom into which there enters only the man who practises what he teaches. Thus where both are to be found we have the Church as it now is; but where only the one kind will be found, there is the Church as it will be, when no evil person will be included. It follows that the Church even now is the kingdom of Christ and the kingdom of heaven.

• Augustine, City of God