The part of Cicero's work which the present age probably finds the most interesting, and the interest of which is, in the nature of things, perennial, has been as yet left unmentioned. It consists of the collections of his private letters from the year 68 B.C. to within a few months of his death. The first of these collections contains his letters to the friend and adviser, Titus Pomponius Atticus, with whom, when they were not both in Rome, he kept up a constant and an extremely intimate correspondence. Atticus, whose profession, as far as he had one, was that of a banker, was not only a man of wide knowledge and great political sagacity, but a refined critic and an author of considerable merit. The publishing business, which he conducted as an adjunct to his principal profession, made him of great use to Cicero by the rapid multiplication in his workshops of copies of the speeches or other writings for which there was an immediate public demand. But the intimacy was much more than that of the politician and his confidential adviser, or the author and his publisher. Cicero found in him a friend with whom he could on all occasions be perfectly frank and at his ease, and on whose sober judgment and undemonstrative, but perfectly sincere, attachment his own excitable and emotional nature could always throw itself without reserve. About four hundred of the letters were published by Atticus several years after Cicero's death. It must always be a source of regret that he could not, or, at all events, did not, publish the other half of the correspondence; many of the letters, especially the brief confidential notes, have the tantalising interest of a conversation where one of the speakers is inaudible. It is the letters to Atticus that place Cicero at the head of all epistolary stylists. We should hardly guess from the more formal and finished writings what the real man was, with his excitable Italian temperament, his swift power of phrase, his sensitive affections.