Paul makes the Resurrection load-bearing: if Christ is not raised the preaching is empty. Good Friday is inseparable — one Triduum, one day — but the tradition named the feast after the rising, not the dying.

Sunday has been kept since Acts 20:7, longer than anything else in the calendar. Still derivative: it is the weekly echo of the annual thing, and Good Friday is half of what it echoes.

The death itself against a feast of the mode of its memorial.