Once a week, I serve Mass for a priest who has learned the EF but who is not allowed to celebrate it publically. I have to serve for him sometimes when nobody else is present, because, as the Mass is not public or announced, the only people who come to it are those whom he or I invite, and there is an understanding that invitations are not a way of making these private Masses public or regular celebrations: anybody who comes thinks it's a secret one-off.
It is hard to express just how special it is to serve a priest when there is nobody else present, especially when he says Mass at a great High Altar which was built as an expression of the triumph of the Holy Sacrifice. The server's role is always subservient to the priest's, but the Priest always emphasises his unworthiness, and as a result, the craftsman and his apprentice, Don Quixote and Sancho, approach the altar as one person who happens to be able to do something he scarcely ought to, and his assistant who worries that he can only get things wrong.
And in amidst the mistakes, the mispronunciations, the difficulties with working out the optional memoria, God appears on the altar and humbles us. After he has had Communion the priest turns and holds up the tiny white focus of light that I am about to recieve and gives me the chance to say on my behalf and on behalf of the odd visitor who happens to be there that we aren't actually worthy just before God gives us Himself anyway.
The moment the server sees which nobody else does comes just before the Consecration: as the priest prepares to bring God to earth, in the final moment before he commences to say the prayer Jesus said, he runs his fingers and thumb along the cloth on which the host is resting to ensure that any speck of anything which might have touched his fingers since the Lavabo, a few minutes before, when they were cleaned, can be removed. How much does what is about to happen matter!