الْعِلْمُ نُورٌ وَالْجَهْلُ ظُلْمَةٌ.
Knowledge is light, and ignorance is darkness.
The contrast between knowledge and ignorance, mirrored by light and darkness, gives the statements an intelligible semantic relation. In rational connection, the mind recognizes a relation such as shared category, correlation, or a contrast that permits both terms to be contemplated together.
Shared meter, spelling, or a final letter is not by itself a rational jāmiʿ. The analyst must articulate the conceptual relation and then test whether waṣl expresses two appropriately related but distinct judgments.