Why were illuminated manuscripts important forms of Gothic art?

Illuminated manuscripts were a major form of artistic production during the Gothic period, serving as a vital medium for both religious and secular expression. Their importance in Gothic art stems from several key factors:1

• Transmission of Ideas: Due to their portability, manuscripts served as an effective means for transmitting artistic styles, iconography, and ideas across different regions and time periods.2
• Parallel to Monumental Art: The development of painting within manuscripts closely mirrored the evolution of monumental painting, often acting as a primary site for stylistic innovation. For instance, the "discovery of light" and the exploration of spatial depth—key trends in Gothic painting—were frequently pioneered or refined by royal illuminators.23
• Artistic Sophistication: These books were highly valued for their beauty and technical mastery, featuring intricate details, refined decoration, and the use of gold leaf. They allowed artists to showcase virtuoso penmanship and complex compositions, ranging from religious scenes to secular themes like chivalric events.123
• Cultural Record: Manuscripts, such as the Très Riches Heures du duc de Berry, remain some of the most eloquent examples of the International Gothic style, preserving the aesthetic values and social interests of the era.1