Communication is a recurring idea in the poem.Each stanza emphasizes that this scene is an awkward goodbye between father and son. Much is felt but little is said. The father is keenly aware of all the things that should be said now, in this moment of parting, and of all the things that, when opportunity was there in the past, were never said. He may be referring to words of love or appreciation or understanding. It is a common experience in human relationships: when the time comes to part from a loved one, either for a short while or permanently, words fail. Feelings are deep and words cannot rise to the occasion.