How is Christ physically manifested in the situation you cited?
We believe He is present in the host and wine via transubstantiation. If he is physically present, in what form?
You are asking questions which give me great delight. That's entirely subjective, I suppose, but I'm grateful and when I wake up at around 2:00 because Clint the super cat is chewing on my toes, I will think of your posts.
My first "essay" in the sense of "attempt": From our POV we have the "I am the bread" discourse, and we have the Synoptic Institution narratives and Paul's narrative (I delivered to you ...) and his remarks.
Leaving aside the question of covenantal blood and communion in two kinds (and I think no one on our side would deny that communion in both kinds is the ideal enactment of the sacrament) we have a lot of lingo about sarx and soma. But we should not ignore the sweeping and comprehensive character of "I am the bread ..."
So we have two tings going on here. First we have what might be thought of as the "fleshly scandal". Sarx and soma are very clunky things. Flesh is, well corpulent or smooth or rough, something most of us desired to touch and to have touch us when hormones were the principle source of authority in out lives. Somata -- well, you must understand that I drive by through the UVA grounds to get to the church where I pray the Rosary and participate in the Mass. So, especially now that Spring is here, Soma and all its glory - as minifested by the excessively nubile gal students and the manifestly hormone-rich guy students - impresses itself on me with all its highly unspiritual (not to say anti-Spiritual) power. I mean, can I get a "hubba-hubba" here? The male menopausal hot flash is a terrible thing, "depend upon it, sir".
And our Lord chooses these notoriously (the world over, I would bet) concepts, flesh and body, for what he is talking about in the places I mentioned.
So, in support of our giving extra "intensity" or something to the kind of "presence" in the Sacrament, I would just say that Jesus uses the most scandalous and troublesome words in the discourses that are clearly (the Synoptics) or possibly (I am the bread) related to the Eucharist.
For the faithful, the concept of "Spirit" and Spiritual" is especially thrilling - just as the wind before a thunderstorm is thrilling. But if we examine the thrill, isn;t it the case that part of it is that the usually so subtle as to be easily ignored air suddenly becomes an invisible power? (We just had devastating tornadoes down the road in Richmond. Pray for those people, please.) My wife and I took our two Great Pyrenees for a walk during the height of a hurricane, and it was stupid, dangerous, and ... WONDERFUL!
But usually and to most people "Spiritual" means something unreal, just as we don't think about the air, unless it's making trouble. When the Gentiles say, "We're with you in Spirit," what they really mean is, "We're not with you at all, but we may think of you if we get bored with whatever we're doing."
So, in terms of the argument, all tis is to say the real deal is not in the verb eimi. It is rather in the rest of the sentence. The "I" of "I am the bread ..." is the same as that of the "there am I in the midst". The eimi (or estin) is, I daresay, I ain't lookin' now) the same.
But the whole overall thing is more urgently awkward and bulky and in the way when soma and sarx are added to the Eimi.
Despite the continuing and deplorable animosity here, we all know and have felt Our Lord's presence when we gather for either formal or informal prayer. When I "read my office" I am "together" with Catholics all over the world, even though I am alone with the cats. And so I am confident, whatever my feelings and experience, that IHS is with me -- and with every Xtian of whatever persuasion who is reading his Bible or saying her prayers and listening for the footfall of the Word.
But in the sacrament, as we pray and as I receive it OR as I "visit" it, there is a concreteness, a "klunkiness", a fullness such as one might expect from the real live "in the flesh" presence of somebody in the room.
In terms of a kind of head-game intellectual problem, I say again that the flesh and body Jesus "currently" has are "Resurrected" flesh and body. And Paul says "it is raised a spiritual body", which as far as I'm concerned is about as illuminating as saying "dry water" or "glowing black". All I know to do in the face of such language is to say, "Yes sir; whatever, sir," and trust that one day God will give me such understanding as is right for me. But I mention this here to take the raw carnality out of what we profess. It is, we think and say, 'Body, Blood, Soul, and Divinity," but it is a spiritual Body and Blood.
Then. of course, there are the Eucharistic miracles. It is of the nature of miracles that they would be so preposterous as to be easily deniable. But from our POV, it seems that once in a while GOd decides to give a little boost to the notion that some wonderful, and incomprehensible change takes place in the Eucharist and that in "a special way", indeed a unique way, Jesus is "there" as He is not "there" in any other case this side of the parousia.
This is not meant to be a persuasive argument but rather a presentation of HOW we think what we think. I hope it is informative.