|[Japanese, 794 - 1185. Collection of the Freer-Sackler.]|
If you look closely at this late-12th-century indigo-dyed paper, you can make out fine ruled lines.
It's a sutra, or Buddhist text, related to the bodhisattva Fugen, but at first glance I was just attracted to the delicate metallic lines on the deepest blue ground and couldn't help imagining how cool it would've been back in elementary school to have silver pencils and spiral notebooks filled with sheets of indigo.
Find more on this Heian period piece, here, along with similar indigo-dyed pages.