Cracking glass and publicly delivering a message need not share any one visible physical form. Their link lies in removing a barrier or state of concealment so that something becomes manifest.
This is a relation of effective disclosure, which is understood intellectually. Hence the source is sensory, the target conceptual, and the common feature conceptual.
A proper analysis states all three components. Merely calling the verse “figurative” or “beautiful” fails to explain the cause of its classification.