How does Edward Hirsch use imagery in Omen?

Much of the imagery is based on flashback. For example, stanza 5 uses the word "boy" to connect seamlessly to the word "boyish" in stanza 4. Also, Hirsch ties the emotions of the speaker's childhood to the friend's experience in the hospital; the airlessness of the hospital connects to the speaker being unable to breathe in his sleep, and the friend's repetitive pain and fear connects to the speaker's emotions during the autumn nights of his childhood. In the concluding stanzas of the poem, Hirsch integrates flashbacks completely within the present narrative by placing the speaker in the same situation as that of his childhood autumn nights. At both points in his life, the speaker sits indoors, sorrowful and enclosed, and waits for the rain to fall on him.