Tomorrow's second reading is 1 Corinthians 15 and begins with St Paul saying:
"Brothers, I want to remind you of the Gospel I preached to you, the Gospel that you received and in which you are firmly established; because the Gospel will save you only if you keep believing exactly what I preached to you - believing anything else will not lead to anything."
A clarion call, you might think, to Orthodoxy: a solid statement that what the Church teaches is what it has always taught; that what it believes is what it has always believed.
Odd, then, that that sentence is optional, at least here, in England and Wales; and at the Vigil Mass I attended this evening, guess what! It was missed out.