William Safire writes at the OUP Blog:

Who was the first blogger?

Hundreds of weblog pioneers will compete for that title, and it will be interesting to see who they will consense upon. (As a language columnist, I feel free to coin a neologism now and then; “consense” is a verb that can replace “form a consensus”. Not the opposite of “nonsense”.)

In the search for the Grand Originator, bloxicographers should not limit themselves to finding the first to use the Internet. “Blogging”, as it will be understood, is broader than “creating a weblog to express a personal opinion and/or to establish an information community.” Although the word “blogosphere” was coined in 1999 by Brad L. Graham “as a joke” and re-minted in all seriousness in 2002 by William Quick with his Daily Pundit, we ought to dig more deeply to place blogging in the great scheme of human communication. That means we should reach back in history to find the person who first popularized the idea of influencing the world by using some medium to get across his ideas to large groups.

The first to suggest a nominee is Joseph Felcone, an antiquarian bookseller in Princeton N.J.. In his most recent catalogue of books for sale, he lists under the headline “The First Blogger?” a book by Plinius Caecilius Secundus, Gaius, better known to all of us as Pliny the Younger, a consul of the Roman empire. The book (a 1518 edition of which, lightly dampstained on a few leaves, is offered for 1400 depreciating U.S. smackers) is titled “Epistolarum libri X. Panegyricus”. We all recognize “epistle” as a letter; according to the Oxford English Dictionary, panegyricus is a “public eulogy”. Thus, young Pliny’s book, one of nine he published between A.D. 99 and 109, would be titled if published today: “Letters in Praise of Great Friends”. The bookseller notes that this Roman consul commented “on political events, social life in Rome and the provinces, and the domestic events of the day. Some letters are paeans of praise for particular friends, whereas others are requests for support of his own agenda…Unlike many of the existing letters of Cicero, Pliny’s letters were intended for public consumption, and are well-crafted from a literary perspective.”

Is this not the definition of the pre-blogger, especially one touting a particular candidate for office or seeking support for his own altruistic ideas or nefarious schemes? Pliny the Younger (son of Pliny the Elder, who ventured too close to the mouth of Mt. Vesuvius) deserves consideration for the title of “First Blogger”.

Others commenting on this OUP blog will put forward the abovementioned Cicero, who preceded the Plinys by a century, famed for his denunciation in the Senate of an assassination conspiracist: “You are not, O Cataline, one whom either shame can recall from infamy, or fear from danger, or reason from madness.” Tough criticism, making today’s sparring between Obama and Clinton look tame, but limited to listeners in the Forum and not disseminated to the wider public — the sine qua non of the blogosphere.

Bloxicographers and blogymologists around the world and elsewhere are invited to comment on my choice and submit their own choices for “first blogger”. By virtue of their participation and scholarship, they will be consider “superbloggers” and their votes will be dispositive no matter who else marshals popular votes for Mulliganicus.
There are those who will complain “who are you, Safire the language columnist, to select the first blogger when you don’t even have a blog, and when you have not even found the ‘first columnist’?”

The fact is, I have. His name is Simeon Stylites the Elder. According to the OED, a stylite was “an ascetic who lived on the top of a pillar”. (Greek “stylos” means “pillar”.)The sainted Simeon the Elder took up residence atop a column in Syria in AD 423. He remained atop that column and others for 37 years, each loftier and narrower than the preceding; his final column was 66 feet high.

Simeon the Elder stood day and night, leaning on a rail, dependent for food on what his disciples (and presumably the Younger) brought him by ladder. He preached sermons to those gathered around his column, who then went out and spread his pastoral teachings. Other columnists took up his technique and were also called stylites. He was the subject of a poem by Tennyson, concluding with “I, Simeon, The watcher on the column till the end.”

That was the first columnist. Now it’s up to you guys: who was the first blogger?

Well, my vote would be for the 'father of Roman Satire': Lucilius ... an excerpt from the Wikipedia article on same pretty much cinches the deal, near as I can tell:

Further, he not only created a style of his own, but, instead of taking the substance of his writings from Greek poetry, or from a remote past, he treated of the familiar matters of daily life, of the politics, the wars, the administration of justice, the eating and drinking, the money-making and money-spending, the scandals and vices, which made up the public and private life of Rome in the last quarter of the 2nd century BC. This he did in a singularly frank, independent and courageous spirit, with no private ambition to serve, or party cause to advance, but with an honest desire to expose the iniquity or incompetence of the governing body, the sordid aims of the middle class, and the corruption and venality of the city mob. There was nothing of stoical austerity or of rhetorical indignation in the tone in which he treated the vices and follies of his time.

His character and tastes were much more akin to those of Horace than of either Persius or Juvenal. But he was what Horace was not, a thoroughly good hater; and he lived at a time when the utmost freedom of speech and the most unrestrained indulgence of public and private animosity were the characteristics of men who took a prominent part in affairs. Although Lucilius took no active part in the public life of his time, he regarded it in the spirit of a man of the world and of society, as well as a man of letters. His ideal of public virtue and private worth had been formed by intimate association with the greatest and best of the soldiers and statesmen of an oldergeneration.

Any other suggestions?