Titled Sekka Zusetsu (雪華図説), this 1832 book of woodblock prints by Doi Toshitsura (1789–1848) reflects twenty years of a life devoted to “snow flowers” (sekka). An Edo-era feudal lord (daimyō), who ruled the Koga Domain in what is today’s Shimōsa Province, he was perhaps the first person in Japan to observe ice crystals under a microscope.

Sekka Zusetsu contains eighty-six firsthand observations of snowflakes as well as a dozen reproduced from J. F. Martinet’s Katechismus der natur (1779). Doi Toshitsura’s process for making his sketches was simple: on a suitably chilly evening, he would place a black cloth outside to pre-cool it with cold air. Then, gathering freshly fallen snow on the blanket, he transferred each flake individually using tweezers to a lacquerware tray for microscopic observation, being careful not to exhale toward his specimens lest they dissolve.

To complete his studies, which he began while still a teenager, he worked closely with Takami Senseki, a scholar of rangaku, literally Dutch learning, a body of knowledge about Western science cultivated from interactions with Netherlandish merchants on Dejima — an artificial island off of Nagasaki, the only territory Western visitors to Japan were allowed to visit during most of the Edo period. It was through this island and its trade network that books like Martinet’s Katechismus made their way into the hands of Japanese scientists.

Doi Toshitsura’s frosty labors with his Dutch microscope eventually earned him the nickname of the Snow Lord, and while his books were privately printed in a limited edition — Sekka Zusetsu was followed by an expanded edition Zoku Sekka Zusetsu in 1840 — his snow-flower patterns were soon incorporated into textiles, tea cups, hairpins, and other ornamented objects. This was partially the result of the inclusion of Doi's diagrams in Hokuetsu Seppu (Snow stories of North Etsu Province), a bestselling 1840 work of human geography on Japanese snow country. Today, you can still see his motifs spread widely across Koga, embedded in sidewalks and public art.