Mary Beard at The New York Review of Books:
The problem about Seneca is that it was always difficult to pin him down (and so it remains). What Tacitus is saying, in his carefully chosen words, is that in his last hours he was “shaping…still” an imago of himself that he had been working on, revising, and adjusting for most of his life, in many different forms. Like it or not, there is something elusive, even a whiff of “spin,” about Seneca.
Romm finds a vivid symbol of that elusiveness in the surviving likenesses of the philosopher (“images” in yet another sense). Before the nineteenth century, the favored image of Seneca (now demoted to “Pseudo-Seneca”) was “a gaunt, haggard, and haunted” portrait sculpture that has survived in several ancient versions. It is not named, but it so matched everyone’s preconceptions of what the elderly philosopher must have looked like that it was simply assumed to be him. In 1813, however, a double-sided portrait—showing two male heads, back to back—was unearthed in Rome, probably dating to the third century AD: one was clearly labeled, in Greek, “Socrates,” the other, in Latin, “Seneca” (“the two sages joined at the back of the head like Siamese twins sharing a single brain,” as Romm has it).