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Konnō Hachiman-gū, a shrine for maths geeks

Never trust an astronomer. They tell you stuff about stardust; tempt you with morsels of celestial beauty; persuade you to ponder the What, the Whence and the Whereto of the universe. Before you can blink, you'll be reading books about maths. Maths! You will understand not one whit, but then again, you barely grasp the phenomenon that is Hello Kitty.

This great crossing of an Einstein-Rosen bridge started …

"It should be possible to continue this path arbitrarily far into the particle's future or past, unless the trajectory hits a gravitational singularity…"

How can you not love that? It's a line from that Wikipedia article. Anyway.

This little adventure started with a calendar; more specifically, this post, in which Massimo writes about "the 364.242190 spins that the planet did in its last revolution around the Sun".

Actually – for this is about science, and one should perforce be precise – it started with this post in February 2012, when I discovered that Japan used to have a leap year, never mind regular leap days.

Then it launched into orbit when I read Massimo's post. I thought of my own, and then I remembered that I'd been wanting to do a Japan astronomy post for aeons. That’s a roundabout way of saying I blame Massimo for this post. Any errors therein, however, are mine, for I am but a humble scribe and not a scientist.

Konnō Hachiman-gū

Look, the point is, there's a shrine for astronomers, or rather mathematicians, but it plays a role in calendars. I know about the connection thanks to a movie about Shibukawa Shunkai (渋川 春海), also known as Shibukawa Harumi (1639 - 1715), who was a Japanese scholar, go player and the first official astronomer appointed to the Tenmongata (Bureau of Astronomy) in the Edo period. During a journey to measure the altitude of the North Star, he noticed errors in the Chinese Hsuan-ming calendar that had been used for 800 years. (It consisted of 354 days. Seven intercalary months were added every nineteen years, but the whole thing was so out of kilter that it couldn't even be used to predict solstices accurately.)

Shibukawa Shunkai (or Shibukawa Harumi).

He started making observations with a gnomon to determine a precise solstice date, but his instruments weren't accurate enough, and he was doomed to fail again and again. He persisted, though, despite resistance from the selfsame court that had appointed him. He eventually revised the Chinese calendar and replaced it with the Jōkyō calendar (illustration below), which was issued in 1684 and calculated the length of the year to be 365.2417 days.

Source: Wikipedia

A book by Shibukawa. Source:

His life was depicted in a movie called Tenichi Meisatsu (天地明察, Insight into the Universe), based on the novel by scifi writer Tow Ubukata and directed by Yojiro Takita, who won a Best Foreign Language Film Oscar in 2009 for his funeral-business drama Okuribito (Departures).

Now we finally get to the shrine! The novel and movie both start at a shrine called Konnō Hachiman-gū, which has stood at this exact location for 390 years.

The shrine is in Shibuya, named after a family that supported Minamoto no Yoritomo in his uprising against the Taira family of Kyoto, and is dedicated to the Minamoto clan deity, Hachiman. It enjoyed long-lasting prosperity thanks to the patronage of Lady Kasuga, nurse of shōgun Tokugawa Iemitsu. Never underestimate the hand that rocks the cradle and the breast that feeds the next ruler.

The shrine was famous for its sengaku (算額 or calculation tablet), wooden tablets that contained geometrical puzzles and were left at various Shinto shrines and Buddhist temples as offerings. Members of all social classes participated: the only requirement was that you had to be a maths geek.
You can see the relevant scene in the movie in this video from 3:25 to 6:25, but it's been uploaded without sound, probably to avoid copyright complaints.

You still spot the odd puzzle at the shrine. When I was there, I noticed two. I took one look and hurried off to consult my university (engineering) students. They frowned, muttered a bit and eventually translated/expounded: "The top and bottom surfaces are parallel, the top is a complete triangle, the height is the square root of 2, and the blue plus pink form one big 3D triangle."

That makes perfect sense. Allegedly. (I have to admit that my response to this was, "Oh. That's it? Isn't it Euclidian origami or at least the final answer as to whether P = NP or not?!")

The second ema is a go puzzle, but none of us – students and I – are go players, and we admitted defeat. We visited the website on the ema, but then decided coffee would be a better call. 

So there you have it. It's a shrine for maths, science, geeks and wacky southern barbarians.

Oh! Wait! Talking of barba … non-Japanese … it's also a shrine with a very special priest: Florian Wiltschko, the first foreigner in Japan to officially qualify as a Shinto priest. He studied Japanology at the University of Vienna, Shintoism at the Kokugakuin University in Tokyo, and then began working at Konnō Hachiman-gū, which is run by the family of a former classmate of his at Kokugakuin.

Read more about him here, here and here.

We're almost done. I started researching this post and mountains of books/encyclopaedias later, most of it irrelevant to this post (of course) [this is me we're talking about], here it is. I'm rather chuffed that it was finished without the help of chocolate, in fewer than 1400 words. I want to end with this poem, and I know the person responsible for this post will agree with me. As beautiful as science is, it's not as perfect as the stars themselves.

When I heard the learn’d astronomer;

When the proofs, the figures, were ranged in columns before me;

When I was shown the charts and the diagrams, to add, divide, and measure them;

When I, sitting, heard the astronomer, where he lectured with much applause in the lecture-room,

How soon, unaccountable, I became tired and sick;
Till rising and gliding out, I wander’d off by myself,

In the mystical moist night-air, and from time to time,

Look’d up in perfect silence at the stars.
–– Walt Whitman

Shibukawa used an astrolabe like this to do his calculations. Source:


1) I've given up with Japanese names: some are first/given/personal name first, some are family name first in this post. It depends on a) how well-known they are outside Japan and b) how pernickety I felt at that particular moment.

2) Maths, British maths, with an s. That ends with a crisp sound, QED. Math peters out into an insipid lisp, like a mouthful of hot porridge, and takes you exactly nowhere.

3) I'm afraid you can't pray for a better head for figures at this shrine, despite its history. (Drat.) Then again, Hachiman is the god of war, and I certainly thought of maths as war when I was at school and especially university. The shrine's Japanese website refers to life's ups and downs, and says the world is a bit of a battlefield. (Ha!) Then it says you can pray, amongst others, for general good fortune, traffic safety and career advancement. It sounds as if the Enterprise NX-01 should pay a visit to Shibuya.

4) Damnit, Massimo!

Konnō Hachiman-gū has beautiful wooden carvings that remind me a bit of Nikkō Tōshō-gū.

Sources and further reading:

Biographical Encyclopaedia of Scientists, Third Edition, edited by John Daintith

Mathematics Across Cultures: The History of Non-Western Mathematics, edited by Helaine Selin

Samurai Art (website)

Self-support of Japanese Astronomy in Edo Period – Seki Takakazu and Shibukawa Harumi by Yukio Ohashi (PDF)

Sumiko Enbutsu, Battle Losses to Fashion Victims (newspaper article)

Co-blogger Sapphire, Calendar-making and math tablets (blog post)

If you're really interested, I recommend a visit to the National Museum of Nature and Science in Ueno Park. See why I live in the shitamachi? 

Edit added 29 January: More beautiful photos and information at Kaori's blog, Kaori Square Feet.

The entrance to the shrine

This is a different shrine, Tamatsukuri Inari Jinja (玉造稲荷神社), which is just next to the Hachiman shrine.

The Inari shrine

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