Printer Aldus Manutius of Venice issued an edition of Virgil in Italic type designed by Francesco Griffo. This was the first book completely printed in Italic type, an adaptation of humanist script. In addition to its elegant design, Italic type had the advantage of a higher character count, allowing more information to be printed legibly in less space than Roman or Gothic type. Aldus’s edition of Virgil was the first of a series of volumes that he issued in the pocket, or octavo format. This smaller format had previously been used for editions of devotional texts, but Aldus was the first to use the smaller format to make non-devotional literature available in the more portable format, and at lower cost. Davies points out that a signifcant reason for Aldus's introduction of the octavo format was the collapse of the credit market in Venice in 1500 caused by "Venetian defeats and Turkish advances," which caused many business failures, and would have motivated Aldus to publish books that could be sold at lower cost.
"The innovation lay not in the small format, often used by printers for devotional texts, but in applying it to a class of literature hitherto issued in large and imposing folios or quartos. It is also certain that the small-format manuscripts in Bernardo Bembo's library included a good number written by the leading Paduan scribe, Bartolomeo Sanvito, whose hand seems to be the best and closest model for the Aldine italic.
"This famous type was a sympathetic rendering by Francesco Griffo of the best humanist cursive script of the day, a wholly new departure in Latin typography but parallel to Aldus's adaptation of Greek cursive hands for his earlier work. If italic has today become practically confined to words that convention dictates be 'italicized', we must also recognize that it appeared to contemporaries as a revelation of elegance -- to Erasmus, 'the neatest types in the world'. The narrow set of the type is also very economical of paper, an important consideration in those days. The very first appearance is in a few words set in the woodcut that adorns the folio St Catherine . . . , followed by limited use in the preface to the second (quarto) edition of Aldus's Latin grammar of February 1501. Italic reached its manifest destiny as the text type of the book which began Aldus's great series of octavo classics, the Virgil of April 1501" (Martin Davies, Aldus Manutius: Printer and Publisher of Renaissance Venice  42).
Aldus' pocket editions of Virgil were a commercial success:
".. . . By the time of the dedication to Bembo in 1514, Aldus had already exhausted two editions of the works of Virgil (which we can estimate to have been about 3,000 for each run). By contrast, nearly all the incunable editions of his Greek folios were still available in the third advertisement of 1513, some at reduced prices. Not that the octavos were cheap—Isabella d'Este, the learned Marchioness of Mantua (and another former pupil of Battista Guarino), sent back some vellum copies she had ordered when she was told by her courtiers that they were worth no more than half the price Aldus's partners were asking. These may have been special illuminated copies costing five ducats or more—some exquisite vellum editions that she did buy from Aldus survive in the British Library—but even the plain paper copies, according to Aldus's annotation of the 1503 advertisement, went for a substantial quarter of a ducat" (Davies, op. cit., 46).