Mystery of the Ineffable
As a layperson, the maximum extent of whose participation has been as a young altar boy, I am no expert - but I did attend Mass every Sunday for the first eighteen years of my life, and I feel that having experienced the Eucharist in this fashion, without preconceived adult ideas and concepts (although those were later super-imposed on my experience), gives me a fairly unique perspective.
The point of the Eucharist is that the ritual allows the participants to tap into accumulated psychic energy of two thousand years of praxis, the flowing river of energy within the collective unconsciousness of untold millions of participants - nothing else in the Western tradition can provide this level of access (especially to simple congregation members). It is a very carefully crafted piece of ritual magic that bypasses the ego consciousness, and taps directly into our most personal selves. In a sense, my perspective makes me very much a religious conservative/traditionalist - I feel that when the liturgy departs from the praxis of our forebears (aside from minor language changes for gender equality and other items that don't affect the substance), we lessen our access to this flow of energy (or at least make it more difficult to tap into)... I felt this, particularly, one time when I visited a Catholic church - the Mass felt like form without substance.
The presence of both congregations and clergy creates a dynamic give and take, and helps broaden and deepen the intensity of the experience. I don't think it is at all meant to be an esoteric thing - yes, it is reserved for those privileged few of us who have taken the first step on our own towards shedding the scales on our eyes, but it is essentially exoteric - not something reserved solely for the initiated.
When things flow well, the energy in the room is palpable, and even transformative (both to congregation and clergy, but especially the latter). The Eucharist creates an altered state of consciousness - especially for those of us who have spent years and years participating in a particular form of it (without ever consciously attempting to memorize, I can recite large chunks of our liturgy from memory - in fact, even now, I stumble over the two or three phrases that were changed sometime in the mid 1980s?), it clears your mind and prepares it for the experience of Gnosis in a way that is structured, and guided.
In my view, this is how the mystery of the ineffable happens in a group setting - each alone must experience it, but the Eucharist allows us to stand on the shoulders of our forebears, all the way back to the original teacher, "Do this is Remembrance of Me" - we are lifted up, and we lift up, lifting each other, we do not lift each other up (to paraphrase a fragment of the liturgy).