But by the cup and baptism, He means the cross; the cup, that is, as being a potion by Him sweetly received, but baptism as the cause of the cleansing of our sins. And they answer Him, without understanding what He had said; wherefore it goes on: “And they said unto Him, We can;” for they thought that He spoke of a visible cup, and of the baptism of which the Jews made use, that is, the washings before their meals.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).