Complex sentence: Nash (2008), 2 By mid-century, demand for illuminated manuscripts declined, perhaps because of the costly production process, especially in comparison to panel painting, although illumination was still popular at the luxury end of the market in the 1460s.
Split into simpler sentences: Nash (2008), 2 By mid-century, demand for illuminated manuscripts declined, perhaps because of the costly production process in comparison to panel painting. Yet illumination was still popular at the luxury end of the market in the 1460s.