The second part of the treatise, commonly called 'De Artibus ac Disciplinis Liberalium Litterarum,' contains so much as the author thought that every monk should be acquainted with concerning the four liberal arts--Grammar, Rhetoric, Logic, Mathematics--the last of which is divided into the four 'disciplines' of Arithmetic, Geometry, Music, and Astronomy. As illustrating the relative importance of these sciences (as we call them) as apprehended by Cassiodorus, it is curious to observe that while Geometry and Astronomy occupy only about one page, and Arithmetic and Music two pages each, Logic takes up eighteen pages, Grammar two, and Rhetoric six. [Sidenote: De Orthographia.] (5) Some other works, chiefly of a grammatical kind[90], which have now perished, together with the exegetical treatises already named, occupied the leisure hours of the old age of Cassiodorus. At length, in the ninety-third year of his age, the veteran statesman, nobleman, and judge crowned his life of useful service by writing for his beloved monks his still extant treatise 'De Orthographia[91].' He tells us that the monks suddenly exclaimed, 'What doth it profit us to study either those works which the ancients have composed or those which your Wisdom has caused to be added to the list, if we are altogether ignorant how we ought to write these things, and on the other hand cannot understand and accurately represent in speech the words which we find written?' In other words, 'Give us a treatise on spelling.' The venerable teacher gladly complied with the request, and compiled from twelve grammarians[92] various rules, the observance of which would prevent the student from committing the usual faults in spelling. It is no doubt true[93] that this work is a mere collection of excerpts from other authors, not arranged on any systematic principle. Still, even as such a collection, it does great credit to the industry of a nonagenarian; and it seems to me that there is much in it which a person who was studying the transition of Latin into the Lingua Volgare might peruse with profit. To an epigraphist especially it must be interesting to see what were the mistakes which an imperfectly educated Italian in that age was most likely to commit. The confusion between _b_ and _v_ was evidently a great source of error, and their nice discrimination, to which Cassiodorus devotes four chapters, a very _crux_ of accurate scholarship. We see also from a passage in the 'De Institutione Divinarum Litterarum[94]' that the practice of assimilating the last letter of the prefix in compound words, like i_l_luminatio, i_r_risio, i_m_probus, though it had been introduced, was as yet hardly universal; and similarly that the monks required to be instructed to write qui_c_quam for euphony, instead of qui_d_quam.