蟻の穴から堤も崩れる
(Ari no ana kara tsutsumi mo kuzureru;
“Even a dike crumbles due to an ant’s burrow”)

Definition:

Big events can arise from small causes. Specifically, even errors, negligence, or lack of attention or preparation that didn’t seem important at the time can cause significant problems down the road. Even a tiny ant-sized hole, if not attended to, can worsen over time and cause the collapse of an entire dike – and thus, presumably, also be responsible for the ensuing flood.

Breakdown:

We begin with the noun 蟻 (ari), “ant,” with the associative particle の (no) marking it as modifying (and possessing) the noun 穴 (ana), “hole.” This in turn is marked by the particle から (kara) as being the source “from” which the following independent clause arises. In this, the noun 堤 (tsutsumi), “embankment,” “dike,” is marked by emphatic particle も (mo), “even,” and implicitly acts as the subject of the verb 崩れる (kuzureru), “collapse,” in conclusive form.

Notes:

This saying comes to us from a Chinese-language philosophical treatise, the Han Feizi (Japanese 『韓非子』 = Kanpishi), which we’ve seen before.

There are a couple of alternate Japanese phrasings of the basic idea, including one that specifies the embankment as being a rather improbable 千里 (one thousand ri, which calculates out to 3,927km or a little over 2,440 miles) in length. Another raises the stakes even further by having the ant-nest destroy 天下 (tenge or tenka): “society,” “the country,” or even “the entire mortal world.” Heavy!

Example sentence:

「蟻の穴から堤も崩れるというように、一文字だけレシピを読み間違えたせいで、デートの為に作っていたケーキが一口も食べられないほど苦くて、大失敗に終わってしまった」

(“Ari no ana kara tsutsumi mo kuzureru to iu you ni, hitomoji dake reshipi wo yomimachigaeta sei de, deeto no tame ni tsukutteita keeki ga hitokuchi mo taberarenai hodo nigakute, daishippai ni owatte shimatta.”)

[“Like a dam brought to ruin by a mere pinhole, because I had misread a single character in the recipe, the cake I was making for the date was inedibly bitter and the whole thing ended up a colossal failure.”]