Of the two sorts of doubt, interdenominational doubt and fundamental religious doubt, Newman does not seem to have suffered from the latter and did not write a great deal about it. What he did write, especially about conscience, is not convincing for a later secular age. What is more fruitful is how Newman related to other doubters of his age: his younger brother Francis who finished a Unitarian, and Matthew Arnold and his younger brother Tom who (twice) became a Catholic. John Newman first shunned his brother but in the end maintained friendly but distant relations with unbelievers. But Victorian doubt was inherited and the real threat to what Newman stood for came from a later generation.