Vision And Echo

I have seen that which sweeter is     Than happy dreams come true.     I have heard that which echo is     Of speech past all I ever knew.     Vision and echo, come again,     Nor let me grieve in easeless pain!     It was a hill I saw, that rose     Like smoke over the street,     Whose greening rampires were upreared     Suddenly almost at my feet;     And tall trees nodded tremblingly     Making the plain day visionary.     But ah, the song, the song I heard     And grieve to hear no more!     It was not angel-voice, nor child's     Singing alone and happy, nor     Note of the wise prophetic thrush     As lonely in the leafless bush.     It was not these, and yet I knew     That song; but now, alas,     My unpurged ears prove all too gross     To keep the nameless air that was     And is not; and my eyes forget     The vision that I follow yet.     Yet though forgetful I did see.     And heard, but cannot tell,     And on my forehead felt an air     Unearthly, on my heart a spell.     I have seen that which deathless is,     And heard--what I for ever miss!