A journey is often used as an extended metaphor of the passage of life itself, of our passing through time. Recognizing that possibility, how would you interpret the deeper or figurative meaning of the poem? A. E. Housman's 'Into my heart an air that kills'

It seems that the speaker is recalling some distant memory with a bit of nostalgia. It might be said that he even sounds melancholic. The reader might get the impression that even his memory is pleasant, he is not able to return there because he had already left. there seems to be some kind of contrast between past and present, which might show the passing of time.