This quotation is a slightly garbled form of what Cassius says to Brutus in Julius Caesar, Act I Scene 2:
Brutus, and Caesar: what should be in that Caesar?
Why should that name be sounded more than yours?
Write them together, yours is as fair a name;
Sound them, it doth become the mouth as well;
Weigh them, it is as heavy; conjure with 'em,
Brutus will start a spirit as soon as Caesar.
Now, in the names of all the gods at once,
Upon what meat doth this our Caesar feed
That he is grown so great?
What Cassius is trying to suggest here is that Caesar has no legitimate basis for the power he has amassed and any future honors that may be given to him. Caesar is a very ordinary man, Cassius claims, and has risen by luck or illegitimate means.