A variation on a theme:

塵も積もれば山となる
(Chiri mo tsumoreba yama to naru; “Even dust, if it builds up, becomes a mountain”)

Definition:

Small things, allowed to accumulate, become large. Multiple sources reference the English saying “Many a little makes a mickle” – a phrase I’d never encountered before in my life – which goes to show something about how languages change over time.

At first glance this kotowaza seems almost identical to last week’s 雨垂れ石を穿つ, but there are a number of important differences. First, the emphasis is on small “things” (which may be metaphorical at least as commonly as they are physical) rather than small amounts of power. Second, the connotation of this saying can be negative: small amounts of work can build up into an overwhelming amount. It appears that the saying began as a Buddhist warning against neglecting small tasks. That said, modern usage allows for both positive and negative implications.

Breakdown:

We get a full sentence this time! The subject is 塵 (chiri, “dust/dirt”), modified by the particle も (mo). While も is often translatable as “also,” “too,” etc., in this case the nuance is closer to “even.” Next comes the verb 積もる (tsumoru, meaning “to pile up,” “to accumulate” – in the intransitive sense) – in the conditional form, which changes its final –ru to -reba. This conjoins the first clause to the second one: next we have the noun 山 (yama, “mountain”) and the verb なる (naru, “to become”). The particle between them, と (to, pronounced like “toe”) is here serving the same function as the English “to,” as in “the dough changes to bread in the oven.” The particle に often serves this function in standard Japanese; と is a more literary or formal alternative.

Notes:

The character 塵 can in some situations be read gomi, meaning “trash,” or “waste,” but in this case that reading would be incorrect. My sources also specifically note that taking 塵 to mean “boring things” is a misinterpretation.

This is another selection from the Edo Iroha Karuta set.

Example sentence:

「塵も積もれば山となるというから、毎日百科事典の記事を一つ読むように決めた」

(“Chiri mo tsumoreba yama to naru to iu kara, mainichi hyakkajitenn no kiji wo hitotsu yomu you ni kimeta.”)

[“They say that even dust can pile up and become a mountain; in that spirit, I decided to read an article out of the encyclopedia each day.”]