The prevailing attitude of the speakers was one of heavy disagreement with a number of things which the reader had not said. - Ronald Knox

All these riches, then, of her theology the Church has acquired, one might almost say, like the British Empire, in a fit of absence of mind. She was so busy scrapping with the heretics that she wasn't conscious of saying anything she hadn't always said; and yet, when she had time to sit down and look about her, she found it took ten minutes to sing the Credo instead of three.

There once was a man who said: "God
Must think it exceedingly odd
If he finds that this tree
Continues to be
When there's no one about in the Quad."

It doesn't do to say that heresy produces the development of doctrine, because that annoys the theologians. But it is true to say that as a matter of history the development of doctrine has been largely a reaction on the Church's part to the attacks of heresy.