He compares the poem to the moon, mainly because of the moon's slow, and gracious movement on the sky. According to the poet, "<span>Leaving, as the moon behind the winter leaves" is the description of how the poem should slowly and carefully flow to the end, just like the moon during a winter night. Poem should be motionless - should capture reader's attention, and entangle him in it completely. </span>
Answer:
To wax is to swell (as in a waxing moon), and to flower is to sprout, and this imagery acts as sexual innuendo, meant to refer to a man's arousal.
