だに・
だに is a literary way to say that merely thinking, hearing, or recalling something is enough to cause a strong reaction. In fixed negative expressions, it says that even the slightest thought or imagining never occurred.
The smallest act is already enough
The key is a scale. Hearing, thinking about, or recalling something is presented as the smallest possible contact with it, yet even that alone produces the reaction. The reaction therefore tends to be strong: fear, pain, grief, disgust, or another intense response.
Two core patterns
With a dictionary-form verb, the expression marks a minimal trigger. With an established noun and a negative form, it emphatically denies that the thought occurred at all.
その鐘の音を聞くだに、滅びた都の記憶が胸によみがえった。
Merely hearing the sound of that bell brought memories of the fallen capital flooding back.
Analyze彼女が自ら真相を語る日が来るとは、誰も想像だにしなかった。
No one had ever imagined that the day would come when she would reveal the truth herself.
Analyzeあの夜の光景は、思い起こすだに胸が痛む。
Merely recalling the scene that night makes my heart ache.
AnalyzeWhat the negative pattern emphasizes
想像だにしない is stronger and more literary than simply saying that someone did not imagine something. It presents imagining as the bare minimum and says that not even this minimum happened. In the past, change only the final verb: 想像だにしなかった.
Choosing among expressions meaning “even”
だに is the most literary and the most restricted of these choices. すら is formal but much more productive, while さえ is the normal productive choice in neutral everyday Japanese. Choose だに only when its established literary tone and minimum-trigger meaning fit the sentence.
More examples
その報告は、聞くだに胸が塞がるものであった。
Merely hearing the report was enough to make one's heart sink.
Analyze故郷を失った日のことは、思うだに涙がこぼれる。
Merely thinking of the day I lost my homeland brings tears to my eyes.
Analyzeあの冬の惨状は、思い出すだに身震いがする。
Merely recalling the horrors of that winter makes me shudder.
Analyzeこの静かな町が戦場になるなど、住民は想像だにしなかった。
The residents had never imagined that this quiet town would become a battlefield.
Analyze彼が王位を捨てるとは、側近たちも夢想だにしなかった。
Even his closest advisers had never dreamed that he would abandon the throne.
Analyzeその計画の全貌は、聞くだに恐ろしい。
The full extent of the plan is terrifying even to hear about.
Analyze