10 But what do You say, O Lord, of Yourself? “Verily, verily, I say unto you, If a man keep my saying, he shall never see death.” You say, “You have a devil.” I call you to life: keep my word and you shall not die. They heard, “He shall never see death who keeps my word,” and were angry, because already dead in that death from which they might have escaped. “Then said the Jews, Now we know that you have a devil. Abraham is dead, and the prophets; and you say, If a man keep my saying, he shall never taste of death.” See how Scripture speaks: “He shall not see,” that is, “taste of death.” “He shall see death— he shall taste of death.” Who sees? Who tastes? What eyes has a man to see with when he dies? When death at its coming shuts up those very eyes from seeing anything, how is it said, “he shall not see death”? With what palate, also, and with what jaws can death be tasted, that its savor may be discovered? When it takes every sense away, what will remain in the palate? But here, “he will see,” and “he will taste,” are used for that which is really the case, he will know by experience.
Source: Tractates on the Gospel of John (New Advent)