سَقَى الْمُعَلِّمُ حُبَّ الْعِلْمِ بِالصَّبْرِ.
The teacher watered love of learning with patience.
The incongruity is between the act of watering and the abstract object, love. The agricultural action is imaginatively applied to education. The mere grammatical agency of a teacher does not by itself establish rational metaphor.
Rational metaphor is generally concerned with altered predication while lexical sense is retained. Here the action itself belongs to an imagined domain. The analyst should state this difference instead of merging two categories.