كَمَثَلِ الْحِمَارِ يَحْمِلُ أَسْفَارًا
Like the example of a donkey carrying books.
The image brings out the distinction between bearing books physically and benefiting from their knowledge. Applied to someone who possesses knowledge but does not attain its intended benefit, the shared respect is an intellectual and composite condition.
The rhetorical point is not merely “a person resembles a donkey.” It is the structured relation between carrying knowledge and failing to benefit from it. Fixating on the physical forms of the two terms would miss the intended argument.