On the 6th of November in 1524, Huldrych Zwingli published his Antwort an den Rat in Zürich über Johannes Ecks Schrift und betreffend den Auschlag der neuen Orte in Frauenfeld.  A typically long title for a typically short response.

Zwingli, never one to mince words, lambasts Johannes Eck.  Though not quite as vociferously as he did in the letter he never sent to the scoundrel.  He nonetheless here lets Eck have it both barrels for his inept attempt to undermine Zwingli’s theology of the Lord’s Supper.

The unsent letter and this particular Flugschrift are beautifully described in vol. 3, pp. 288-300 and in Mörikofer’s absolutely peerless biography of Zwingli (2, 19ff).