There are only two verses to this poem by Christina Rossetti, which are these:
Who has seen the wind?Neither I nor you:But when the leaves hang trembling,The wind is passing through.Who has seen the wind?Neither you nor I:But when the trees bow down their heads,The wind is passing by.
In the first verse, she asks, rhetorically, if anyone has seen the wind and answers herself, saying no one has ever seen the wind. The question is considered rhetorical because Rossetti expects no answer from her reader. Everyone knows the wind cannot be seen. The next two lines explain that we can see the evidence of the wind's existence through the movement of the leaves passing through them. In the second verse, she repeats and answers her rhetorical question, and then presents additional evidence of the wind in the next two lines, the trees nodding from the force of the wind.
The wind in the poem can be reasonably interpreted to be a metaphor for God, whom we cannot see, but whose presence we can find evidence of in nature. Rossetti's writings were often focused on spirituality, and this poem is a good example of her use of symbol for her spiritual ideas. She had a difficult life in many ways, with serious physical ailments, a brother who was mentally ill, and the loss of other close family members. So, as many people have, she took solace in spirituality.