The bread becomes the "Body, Blood, Soul, And Divinity" of Christ when the priest completes the words of Institution pertaining to the Body. And the wine, mutatis mutandis, ditto.
As to the appearance, first, who knows what a Spiritual Body or Spiritual Blood look like?
Second, what a thing IS, it's substance, is different from what a think LOOKS like (tastes like, feels like, etc.).
"Star differs from star in glory" but they are all stars. One can be a gas giant. Another can be a dwarf star. They are all stars, even the ones that no longer shine.
As I have said before, a wedding ring can be gold, silver plated with gold, platinum, or who knows what. But when a disaster happens the wife does not say, "Help, my gold annulus fell in the garbage disposal." She says, "My wedding ring ...." the shape, with room for variations, like embedded jewels, is variable and unimportant, except that it needs to be vaguely donut shaped to serve as a ring. The stuff it's made of is unimportant. Gold, platinum, who cares? The "esse", the "what it IS," the "substance" is "wedding ring," and that's why the wife is in a dither, because of what it is, not because of what it looks like.
It is the "what it is" of the bread and wine which are displaced by the "what it is" of the Body, Blood, etc.
So that's why the appearances are unimportant and do not effect the Sacrament.
HOWEVER, sometimes there are Eucharistic miracles, and links to at least one of them were recently posted.
Now if you EVER say again that nobody ever answers the question, rules or no rules, I will call you a liar. I have posted these exact arguments before more than once on this forum.
Thanks Dawg. I was hoping to continue this discussion.
I would add:
Why does the bread still bear the characteristics of bread is quite similar to asking “Why does the Word made flesh, still look like flesh?”
St. Thomas used substances and accidents to explain, but that is not so much an explanation as it is a re-description. In the East, they feel no need for it, it just is. And that is sufficient, according to Scripture.
All that said, another way to look at it is in our own experience. If a Protestants thinks of the moment after they were “reborn”. They are a new person - substantially different, different by an order of magnitude. Yet no microscope, blood test, or chemical analysis of their organs or cells will be any different than before they were born again.
If we wish to understand the how of the Holy Eucharist in a similarity to something else we experience or know, we need only look to our own transformation or to the Incarnation.