눈에 핏발이 서다.

The Korean idiom '눈에 핏발이 서다' (nune pitbari seoda) literally translates to 'blood streaks stand in the eyes.' This vivid imagery directly conveys the physical manifestation of intense emotions or physical strain. The word '눈' (nun) means 'eye.' '핏발' (pitbal) is a compound word: '피' (pi) means 'blood,' and '발' (bal) here refers to 'streaks,' 'strands,' or 'lines.' So, '핏발' specifically describes the red lines or blood vessels that become prominent in the whites of the eyes. '서다' (seoda) is a verb meaning 'to stand,' 'to rise,' or 'to be erect.' In this context, it emphasizes the visibility and distinctness of the blood streaks. Historically, expressions linking physical bodily reactions to emotional states are common across many languages. In Korean culture, the eyes are often considered a window to one's soul and emotional state. Therefore, a physical change like bloodshot eyes is immediately associated with strong internal conditions. The idiom likely emerged from observations of how the human body reacts to extreme states. When someone is very angry, blood pressure can rise, causing capillaries in the eyes to dilate or even rupture slightly, leading to visible red streaks. Similarly, severe fatigue or prolonged stress can also cause eye strain and dryness, making blood vessels more noticeable. The phrase captures this physiological response eloquently. While the exact textual origin or first recorded use is difficult to pinpoint without extensive historical linguistic research, the components of the phrase ('눈,' '피,' '발,' '서다') are all ancient Korean words, suggesting that the idiom itself has deep roots in the language. It reflects a long-standing understanding of human physiology and emotional expression within Korean society. Over time, '눈에 핏발이 서다' has become a conventional way to describe a state of intense anger, extreme exhaustion, or significant stress, where the physical symptom of bloodshot eyes is a clear indicator of the internal turmoil.