(Nakanu hotaru ga mi wo kogasu; “The silent firefly burns itself”)
Those who feel the most deeply are silent, while those who talk the most are often shallow in their thoughts and feelings. “Light cares speak, great ones are dumb.” “Still waters run deep.” In the insect world, some (especially cicadas; see below) are impressively loud… but the voiceless firefly glows as if it were burning up inside.
The saying may be used for thoughts and feelings in general, but is most often applied to love or romantic attraction. Keep in mind the traditional idealized image of the stoic samurai man, and the 大和撫子 (Yamato Nadeshiko) woman who is so silent and retiring as to be nearly nonexistent. I’m reminded of the famous assertion (apocryphally attributed to Soseki) that the best Japanese translation for “I love you” would be 月がきれいですね (tsuki ga kirei desu ne), “The moon is beautiful, isn’t it.”
We begin* with the noun 鳴く (naku), “to make an animal sound,” in imperfective form. It then takes the negative suffix ず (zu), in prenominal form as ぬ (nu), which allows it to connect to and modify the noun 蛍 (hotaru), “firefly.” Particle が (ga) marks the silent firefly as the subject of a verb; particle を (wo) marks the noun 身 (mi), “body,” “one’s self,” as its direct object. The verb in question is 焦がす (kogasu), “to burn (something).”
*A longer version of the saying begins with 鳴く蝉よりも (naku semi yori mo), “much more than the cicada, who does call.”
I have mixed feelings about this saying. On the one hand, it certainly is true that people with absolutely nothing in their hearts will overcompensate with bombastic and excessive talk about the feelings they think they’re supposed to have. (Cf. 45.) And at the same time, the more deeply-held a feeling is, the harder it can be to put into words. On the other hand, humans are social animals and communication is of vital importance to our inner and outer lives. If you take this saying as mere description, it’s fine, but anyone who takes it as prescriptive, or romanticizes silence, and avoids the work of proper expression is only hurting themselves.
(“Nakanu hotaru ga mi wo kogasu you ni, uchi no musume ga betsu no kurasu no otoko no ko ni kataomoi wo shiteite, mainichi sakkaa de medatsu you ni funrei doryoku shiteru rashii.”)
[“Apparently our daughter, like the fabled firefly who burns bright but doesn’t call out, has developed a one-sided crush on a boy in a different class, and has been working as hard as he can every day to stand out in soccer.”]