It is easy to fear something too little, or too much. But it seems rather difficult to fear it justly.
--TERADA Torahiko (1935) (my translation from Japanese).
This epigram by TERADA Torahiko (physicist and essayist, 1878-1935) is recently often quoted, particularly by those who study risk of radioactivity or of chemicals. It seems that they follow KONDÔ (1985, 1998), who placed the quotation at the beginning of his book discussing the hazard of radioactivity. But he did not mention the original location of the phrase.
Fortunately, most of TERADA's essays
have been digitized and placed online by a voluntary project "Aozora Bunko"
(http://www.aozora.gr.jp/).
Thanks to the project, I was able to locate the quotation by full-text search.
[[I needed to try some different spellings, however. The word "kowagaru" (to fear) was spelled all in Japanese hiragana characters in the text found in Aozora Bunko (which followed the Iwanami Bunko edition typeset in 1963) while a Chinese character was used in the quotation by KONDÔ. I am not sure which spelling was used in the original publication in 1935.]]
TERADA must have had the most advanced knowledge as of his time about radiation. He had studied X-rays. Indeed, he interpreted X-ray diffraction caused by crystals similarly to and independently of Lawrence BRAGG though his publication (in 1913) happened to be a little later (KOYAMA, 1998). But the actual context of the epigram was not radiation.
It was a series of volcanic eruptions. He was not directly engaged in scientific investigation of volcanoes, but he was something like an advisor to it. (After the work on X-rays, TERADA's attention turned to what would later be called "physics of complex systems" which included a broad range of geophysics.) It was incidental that he encountered two minor eruptions of Mount Asama, but then he made a narrative of what he saw, heard and thought, in his renowned prose. The epigram was originally a remark after hearing a traveller who told his experience to an officer of a railway station. To the author as well as to the station officer, the traveller's "nothing to worry" assertion seemed "to fear the volcano too little".
The sentence in the original essay next to the quoted one is curious: "I feel so toward XXXX of XX or toward YYYYY of YY as well.", thus containing symbols for unprintable words. Those words were hidden probably because they were politically sensitive. I imagine, they may have meant communism of USSR, colonialism of European countries, fascism of Italy and Germany, or aggressiveness of Japanese army at the time. After the end of the Second World War, there was probably no more need to hide them, but the author had passed away and the editor of the collection could not decipher them.
Anyway, it seems sure that the epigram is meant to cover a wide range of affairs, not just volcanic eruptions.
[[TERADA is also known by another epigram, "Natural disasters come along when we forget about them." This exact phrase is not found in his writings, but it is certain that he often said something like that (NAKAYA, 1955).]]