A man was noble who could reckon a Consul, a Praetor, or an AEdile among his ancestors.

Such was not the case with Cicero.

As he filled all these offices, his son was noble--as were his son's sons and grandsons, if such there were.
It was common to Romans to have three names, and our Cicero had three.
Marcus, which was similar in its use to the Christian name of one of us, had been that of his grandfather and father, and was handed on to his son.

This, called the praenomen, was conferred on the child when a babe with a ceremony not unlike that of our baptism.

There was but a limited choice of such names among the Romans, so that an initial letter will generally declare to those accustomed to the literature that intended.
A.stands for Aulus, P.for Publius, M.generally for Marcus, C.for Caius, though there was a Cneus also.