the.com/pillow book

means A personal notebook of jotted observations, lists, gossip, and musings kept close at hand — the original genre of the miscellany, named after Sei Shōnagon's 'Makura no Sōshi.'

from From the Japanese 'makura no sōshi' — literally 'pillow' (makura) + 'book/notes' (sōshi). The leading theory is that such notebooks were kept tucked near one's pillow or in a drawer of the wooden pillow-stand used in Heian-era Japan, ready for private jottings at the start or end of the day. Sei Shōnagon's own 11th-century example — a dazzling scattershot of lists, grudges, and observations from inside the imperial court — became so definitive that 'pillow book' turned from one woman's diary into an entire literary genre.