also: ろばのはし
pons asinorum; donkey bridge; learning hurdle
A metaphor for a difficult obstacle in learning, especially a concept that blocks progress until it is understood. The term comes from the Latin 'pons asinorum' (bridge of donkeys), originally referring to a geometry theorem. In Japanese, it is a direct translation used in educational or philosophical contexts.
This theorem is a pons asinorum for many students.
Once you get past the donkey bridge, the rest of the learning becomes easier.
Standard modern spelling using katakana for 'donkey'.
Kanji spelling using 驢馬 for 'donkey'; 驢 is a non-jōyō character and this form is very rare in modern writing.
Calque from Latin 'pons asinorum' (bridge of donkeys), a term used in medieval logic and geometry for a difficult proof or concept that separates capable students from those who struggle. The Japanese form is a direct translation, likely introduced through Western educational texts.