In the domain of history and biography he was somewhat less active. He wrote, however, memoirs of his campaigns, and a short biography of Pompey. A work of his, first mentioned by Cicero, to which peculiar interest attaches, is the _Imagines_ or _Hebdomades_, called by Cicero "_Peplographia_ Varronis." [27] It was a series of portraits--700 in all-- of Greek and Roman celebrities, [28] with a short biography attached to each, and a metrical epigram as well. This was intended to be, and soon became, a popular work. An abridged edition was issued shortly after the first, 39 B.C. no doubt to meet the increased demand. This work is mentioned by Pliny as embodying a new and most acceptable process, [29] whereby the impressions of the portraits were multiplied, and the reading public could acquaint themselves with the physiognomy and features of great men. [30] What this process was has been the subject of much doubt. Some think it was merely an improved method of miniature drawing, others, dwelling on the general acceptableness of the invention, strongly contend that it was some method of multiplying the portraits like that of copper or wood engraving, and this seems by far the most probable view; but what the method was the notices are much too vague for us to determine. The next works to be noticed are those on practical science. As far as we can judge he seems to have imitated Cato in bringing out a kind of encyclopaedia, adapted for general readers. Augustine speaks of him as having exhaustively treated the whole circle of the liberal, or as he prefers to call it, the secular arts. [31] Those to which most weight were attached would seem to have been grammar, rhetoric, arithmetic, medicine, and geometry. From one or two passages that are preserved, we should be inclined to fancy that Varro attached a superstitious (almost a Pythagorean) importance to numbers. [32] He himself was not an adherent of any system, but as Mommsen quaintly expresses it, he led a blind dance between them all, veering now to one now to another, as he wished to avoid any unpleasant conclusion or to catch at some attractive idea. Not strictly connected with the _Encyclopaedia_, but going to some extent over the same ground though in a far more thorough and systematic way, was the great treatise _De Lingua Latina_, in twenty-five books, of which the first four were dedicated to Septimius, the last twenty-one (to the orator's infinite delight) to Cicero. Few things gave Cicero greater pleasure than this testimony of Varro's regard. With his insatiable appetite for praise, he could not but observe with regret that Varro, trusted by Pompey, courted by Caesar, and reverenced by all alike, had never made any confidential advances to him. Probably the deeply-read student and simple-natured man failed to appreciate the more brilliant, if less profound, scholarship of the orator, and the vacillation and complexity of his character. While Cicero loaded him with praises and