Writings by Renaissance artists are often prized for the light they can shed on artists' lives and personalities. Despite their nearly equal life spans and impressive artistic output, Michelangelo, whose surviving writings are copious, is accessible in a way that Donatello is not. Other artists now less appreciated for their oeuvres, such as Cennino Cennini, are of greater value to modern historians for their written than for their painted output. The great paradox, however, is Leonardo da Vinci, who left thousands of pages of writing. These texts have been categorized for study, segmenting his body of writings into smaller groupings on subjects such as painting, science, anatomy, optics, and engineering. Yet despite the exhaustive application of this method, Leonardo, as an individual, remains thoroughly obscure.