Luke 11:30

(in Esai. 7.) A sign is a thing brought openly to view, containing in itself the manifestation of something hidden, as the sign of Jonas represents the descent to hell, the ascension of Christ, and His resurrection from the dead. Hence it is added, For as Jonas was a sign to the Ninevites, so shall also the Son of man be to this generation. He gives them a sign, not from heaven, because they were unworthy to see it, but from the lowest depths of hell; a sign, namely, of His incarnation, not of His divinity; of His passion, not of His glorification.

That you may know that the people of the Synagogue are treated with dishonour, while the blessedness of the Church is increased. But as Jonas was a sign to the Ninevites, so also will the Son of man be to the Jews. Hence it is added, They seek a sign; and there shall no sign be given them but the sign of Jonas the prophet. Now as the sign of Jonas is a type of our Lord's passion, so also is it a testimony of the grievous sins which the Jews have committed. We may remark at once both the mighty voice of warning, and the declaration of mercy. For by the example of the Ninevites both a punishment is denounced, and a remedy promised. Hence even the Jews ought not to despair of pardon, if they will but practise repentance.

(de Cons. Ev. lib. ii. c. 39.) Luke indeed relates this in the same place as Matthew, but in a somewhat different order. But who does not see that it is an idle question, in what order our Lord said those things, seeing that we ought to learn by the most precious authority of the Evangelist, that there is no falsehood. But not every man will repeat another's words in the same order in which they proceeded from his mouth, seeing that the order itself makes no difference with respect to the fact, whether it be so or not.