Help with ysis of the poem Echo by Christina Rosetti?

'eyes as bright as sunlight on a stream' is a simile. The last three lines are a metaphor for love making: the rhythm of pulse, breath the actual act and the 'speak low, lean low' the physical side of carnal union. This is a lover yearning for anything from his or her dead lover. 'Yet come to me in dreams, that I may live/My very life again though cold in death;' Her lover is gone forever but even in her dreams she wishes to once again experience those last three lines of the poem again, that is to say the physical as well as the spiritual union that they once had.