Drusus knew that in all Caesar's correspondence a cipher had been used which consisted merely of substituting for each letter the fourth letter beyond it, as D for A; and a little examination showed that the present cryptogram was made on the same rude method.

After a few guesses he struck the proper substitutions, and was able to read.
"Pompeius Magnus, Imperator, to the most excellent Lucius Domitius Ahenobarbus, Rome, tenth day before the Calends of January.

If it is well with you, it is well; I am well.[134] I write to warn you that we are told that Quintus Drusus, your personal enemy and the friend of our own foes, is in Campania.

We need not add more, for we trust to you to see to it that he stirs up no faction in favour of his master in those parts.

Be assured that you will not be long troubled by this enemy.