Huldrych Zwingli published his ‘clear explanation‘ on the 23rd of February, 1526 with the publishing house of Froschauer in Zurich.
In it he goes into extensive detail discussing the pivotal phrase ‘this is my body’ in four parts- 1) the false understanding of the phrase, 2) Scriptural evidence against the false understanding, 3) the right scriptural understanding, and 4) further proofs.
The booklet was written in German (so that the ordinary folk could read it) and not in Latin (because he wanted the truth widely disseminated and not merely debated amongst the theologians). It is prefaced by Zwingli’s motto, Matthew 11:28.
Δεῦτε πρός με πάντες οἱ κοπιῶντες καὶ πεφορτισμένοι κἀγὼ ἀναπαύσω ὑμᾶς.
And it concludes with a little poem
Sag mir an, ob du’s weist,
Das vatter, sun und geist,
Fleisch und blut, brot und wyn
Als sampt ein got mög sin?