How did Renaissance book designers use ancient Roman lettering as inspiration?

Renaissance book designers and humanists sought to restore what they perceived as their lost Classical heritage by rejecting medieval black-letter scripts in favor of styles they believed originated in ancient Rome. Their inspiration and methods included:123

• Manuscript Research: Humanist scholars collected ancient Roman artifacts and manuscripts. They mistakenly believed that 9th- to 12th-century Carolingian manuscripts—which featured titles in pen-made Roman capitals—were authentic ancient Roman scripts.2
• Calligraphic Adaptation: Scribes like Poggio Bracciolini developed "humanist book hands" based on these Carolingian models. To complete these scripts, they added pen-made square capitals modeled after those found on early Roman monuments, effectively linking the two styles.2
• Epigraphic Study: Later in the 15th century, enthusiasts compiled sillogi (anthologies of Roman inscriptions) to provide precise models for square capital letters.2
• Geometric Construction: Designers like Felice Feliciano and Albrecht Dürer attempted to codify the construction of monumental Roman capitals using geometric rules, often employing a straight edge and compass to replicate the proportions of inscriptional lettering.2
• Typeface Development: Printers such as Nicolas Jenson and Francesco Griffo translated these calligraphic and epigraphic studies into "roman" typefaces, which became the standard for Renaissance book design.145