Lost Echo sits amid the voiceless mountains, And feeds her grief with his remember'd lay, And will no more reply to winds or fountains, Or amorous birds perch'd on the young green spray, Or herdsman's horn, or bell at closing day; Since she can mimic not his lips, more dear Than those for whose disdain she pin'd away Into a shadow of all sounds: a drear Murmur, between their songs, is all the woodmen hear.
Time to meet even more mourners, gang. "Echo" is so depressed about Adonais' death that she decides not to respond to wind, fountains, bird, grass, the "herdsman's horn," or bells that ring at the end of the day. She just straight-up ignores them.
She's sad because she can't "mimic his lips." She wishes she could make his voice echo, but since she can't, she's not going to make anything echo anymore.
His voice was more dear to her than the rest of the world's, who don't even appreciate echoes. They just think of her echoes as a "drear murmur."
Man, that's a whole lot of personification going on. Is Shelley having nature mimic his own grief?