Da Vinci's Last Supper
"Therefore, we should hold steadfastly to these clear words of our Lord, The bread he proffers is his Body, and the cup or wine is his Blood, or the New Testament in his Blood. In childlike faith we should partake, without doubting, and believe it to be so. We should give thanks to Christ for such grace, rejoice over it, and strengthen our hearts by it, considering why Christ has done what he did, not disputing whether he is abel to do it. Impertinent are the hearts which question why Christ did it this way and doubt that he is abel to do it."
Maundy Thursday Sermon, Martin Luther, 2 April 1534. Sermons of Martin Luther, House Postils, vol. 1, 456.