Where does “絵筆” come from?

絵筆 (Japanese) comes from Japanese 筆, from Japanese 文, from Middle Chinese 文.

Ancestry of “絵筆”, step by step

Step	Language	Word	Meaning
1	Japanese	筆	a writing brush, a painting brush, a pen;...
2	Japanese	文	the mon, an old currency; a unit of length for...
3	Middle Chinese	文	—

絵筆 — Etymology, Origin & Word History | Etymology Explorer