Beware lest your calculations be all messed up
(Ichinan satte mata ichinan; “One trouble goes; another trouble.”)
No sooner have you escaped one danger or difficulty than the next arises. Out of the frying-pan and into the next frying-pan. Alternately, a state of discombobulation arising from being hammered by an unrelenting string of disasters. A warning to be on guard even after a problem has been overcome, and a comment on how life is full of troubles. Compare and contrast 前門の虎後門の狼 and 泣き面に蜂.
We begin with number-noun 一難 (ichinan), “one hardship,” “one disaster.” Any particles are elided, but this is the subject of the verb 去る (saru), “to leave,” which appears in conjunctive form, signaling a shift to a dependent clause. This clause begins with adverb また (mata), “again,” and ends with a repeat of number-noun 一難, with any verbs or copulae elided.
It is acceptable for 去る to appear in perfective form with conditional particle ば (ba) as 去れば (sareba), “when one trouble leaves,” with or without the また included. However, replacing the verb with 過ぎる (sugiru), “to pass [by],” in either form is considered an error.
(“Tsuugaku tochuu de jitensha no taiya ga panku shite, naoshita totan ni niwakaame ni furarete, yatto gakkkou ni tsuita to omottara kondo wa shukudai ga nai koto ni kidzuita. Sonna choushi de kyou wa asa kara zutto ichinan satte mata ichinan da.”)
[“On the way to school my bike got a flat tire, and as soon as I’d fixed it I was caught in a sudden rainshower, and then when I’d finally gotten to school I realized that my homework wasn’t in my bag. And that’s how it’s been all day, just one thing after another.”]