Schmemann's main point, in my reading of the book, is this: The Eucharist is the entire service, the whole of the Liturgy.
The image of the cross immediately brings to mind that sacrifice. That symbol has been imbued with a power beyond mere words. Likewise the bread and wine of communion have been imbued with power. Jesus said we must eat his flesh and drink his blood.
A modern American low church, nondenominational experience seems like a bland saltine cracker compared to the majestic cake of ancient rites and liturgy.
Wherein I explain the Anglican portion of Amateur Anglican
Where it comes from
Feed my sheep
Wherein I try to explain why traditions matter