There were seven pictures and panegyrics in each book, whence the whole work has been called Hebdomades. Varro had adopted the superstitious notions of the ancients concerning particular numbers, and the number seven seems specially to have commanded his veneration. There were in the world seven wonders—there were seven wise men among the Greeks—there were seven chariots in the Circensian games—and seven chiefs were chosen to make war on Thebes: All which he sums up with remarking, that he himself had then entered his twelfth period of seven years, on which day he had written seventy times seven books, many of which, in consequence of his proscription, had been lost in the plunder of his library. It appears from Ausonius, that the tenth book of this work was occupied with pictures and panegyrics of distinguished architects, since, in his Eidyllium, entitled _Mosella_, he observes, that the buildings on the banks of that river would not have been despised by the most celebrated architects; and that those who planned them might well deserve a place in the tenth book of the Hebdomas of Varro:— “Forsan et insignes hominumque operumque labores Hic habuit decimo celebrata volumine Marci Hebdomas.” —— It is evident, however, from one of the letters of Symmachus, addressed to his father, that though this was a professed work of panegyric, Varro was very sparing and niggardly of his praise even to the greatest characters: “Ille Pythagoram qui animas in æternitatem primus asseruit; ille Platonem qui deos esse persuasit; ille Aristotelem qui naturam bene loquendi in artem redegit; ille pauperem Curium sed divitibus imperantem; ille severos Catones, gentem Fabiam, decora Scipionum, totumque illum triumphalem Senatum parca laude perstrinxit.” Varro also wrote an eulogy on Porcia, the wife of Brutus, which is alluded to by Cicero in one of his letters to Atticus. Among his notices of celebrated characters, it is much to be regretted that the _Liber de Vita Sua_, cited by Charisius, has shared the same fate as most of the other valuable works of Varro. The treatise entitled, _Sisenna, sive de Historia_, was a tract on the composition of history, inscribed to Sisenna, the Roman historian, who wrote an account of the civil wars of Marius and Sylla. It contained, it is said, many excellent precepts with regard to the appropriate style of history, and the accurate investigation of facts. But the greatest service rendered by Varro to history was his attempt to fix the chronology of the world. Censorinus informs us that he was the first who regulated chronology by eclipses. That learned grammarian has also mentioned the division of three great periods established by Varro. He did not determine whether the earliest of them had any beginning, but he fixed the end of it at the Ogygian deluge. To this period of absolute historical darkness, he supposed that a kind of twilight succeeded, which continued from that