«وَأَسْبَابُهُ أَيْ أَسْبَابُ التَّقَارُنِ فِي الْخَيَالِ مُخْتَلِفَةٌ»
And the causes of that association differ.
A calligrapher may associate a pen with an inkpot, while a student associates a book with a classroom. Such links depend on prior encounters. Someone without the relevant experience may not make the same association.
Thus imaginative linkage changes with audience, place, time and custom. It does not operate as an equally necessary universal logical principle for everyone.