As the overview article showed, before Genkai, Japan had nothing resembling a modern national dictionary. This article looks at the most basic innovation Genkai brought — the principle of arrangement itself.
How earlier wordbooks were arranged
The Setsuyōshū, a wordbook widely used in Japan through the Edo period, sorted words by meaning into categories — “heaven and earth,” “seasons,” “human relations,” “language,” and so on — and arranged them further within each category by iroha order or other criteria. In other words, to look up a word, you first had to already know which semantic category it belonged to.
This suited a practical use — checking the correct kanji for a word you already more or less knew — but it was poorly suited to what is, today, the most basic use of a dictionary: looking up the meaning of a word you don’t know.
All you need to know is “a, i, u, e, o”
Genkai adopted an entirely different principle. With no regard whatsoever for a word’s meaning, it arranged every word in a single sequence using only its first sound as a guide, following the gojūon (fifty-sound) order — a, i, u, e, o, ka, ki, ku, and so on.
The strength of this approach lies in its simplicity. The person looking a word up doesn’t need to know anything about its meaning beforehand. As long as they know how the word is pronounced, following the gojūon sequence will always lead them to it. This mechanism, now so taken for granted it goes unnoticed, was in fact an invention that reshaped what a dictionary is used for.
The simpler the idea, the harder it is to carry out
That said, the idea of “arranging in gojūon order” wasn’t itself entirely new — the gojūon chart is thought to originate with Heian-period Buddhist scholar-monks, who organized it under the influence of Sanskrit phonology (Siddham studies), and Edo-period scholars of Japanese classical studies were already fluent in using it. Ōtsuki’s task was to apply this gojūon framework, consistently and by rule, across an entire vocabulary of tens of thousands of words — patient, painstaking work on an enormous scale. Where do long vowels, contracted sounds, and geminate consonants belong in the order? How should voiced and semi-voiced sounds be handled? Without settling every one of these details, gojūon order remains a nice idea on paper, nothing more.
Summary
| Point | Detail |
|---|---|
| The earlier approach | Words arranged by semantic category — unusable without already knowing the category |
| Genkai’s approach | Every word arranged in a single sequence, using only its pronunciation (initial sound) as a guide |
| The resulting change | Made possible the most basic use of a dictionary today: looking up a word you don’t know |
In a nutshell — the simple idea of ordering words “a, i, u, e, o” is what turned the dictionary from a tool for people who already knew, into a tool for people who wanted to find out.