powerful imagination of the speaker of this poem as he envisages his rural retreat and the images of natural beauty that he will enjoy lends itself naturally to great imagery. In particular, one of the distinct aspects of this poem are the sounds that are created as part of the imagery. Consider the second stanza:

And I shall have some peace there, for peace comes dropping slow,

Dropping from the veils of morning to where the cricket sings;

There midnight's all a glimmer, and noon a purple glow,

And evening full of the linnet's wings.

Note the way we have combined images that appeal to our sight, with the description of midnight being "all a glimmer" and noon being "a purple glow," but also we have images that directly appeal to our sense of hearing with the sounds of the crickets and the beating of the linnet's wings. Such imagery that appeals to a variety of senses really helps us to imagine the scene and places us there so we can share in the peace and beauty of this man's rural retreat.

In this poem, the speaker is making plans for a change in life location and style. S/he has had enough of living in the midst of traffic and the noise and bustle of life in close proximity with other people. It is time to get away and to simplify.

The language and the imagery, as an expression of this desire to simplify, is very expressive but not at all flowery or overdone. There is no lengthy description of the new dwelling; we're just told it will be a "small cabin" made of very basic materials. The plan for food at this new location is also straightforward - nine rows of bean plants and a hive for honey bees. Very simple, very basic, but very adequate - the speaker is conveying the desire for simplicity through images and through the manner in which they are explained.

No need to go on at great length. The speaker expresses the "deep heart's core" need to find a place where the loudest sound is the "lake water lapping with low sounds by the shore." With very simple word pictures, Yeats very effectively communicates the anticipation of the freedom to be found when the speaker arrives at Innisfree.

The cabin on the lake symbolizes the simple life, a life free of distraction and troubles.  Symbolism is an object that has a meaning larger than itself.  Just as the cabin is simple, “of clay and wattles made,” this life allows us to rely on nothing more than ourselves.  We have, as is repeated in the poem, “peace there.”  Peace, solitude, and nothing but the sound of the waves lapping?  What could be more simple.

A theme in the poem is mankind’s love of nature.  Theme is a message.  From nature we came, and to nature we long to go back.  This is why we go camping and hiking, and take long walks and bike rides.  The fact that the cabin is made of natural materials emphasizes this connection to nature.  So is what’s outside the cabin.

Nine bean rows will I have there, a hive for the honey bee,

And live alone in the bee-loud glade.

You can see it in the emphasis on peace, solitude, returning to the land, and living off the land.  This is what people often want, the ability to be one with the land.  It might be gardening or simply taking a walk, but this poem captures that wish. 

An example of personification is “where the cricket sings.”  Personification is when you describe something like a human when it’s not.  Crickets do not literally sing.  They make a sound like music, which we describe as human-like singing.

Imagery is descriptive language.  It can be sensory language, such as “cricket sings” and “pavements grey.”  One appeals to the sense of sound, and the other the sense of sight.  You can also hear the crickets sing, linnet’s wings, and bees buzz, and see the nine rows of beans and purple glow.

The poem paints a pretty picture of a simple little cabin by a lake.  Like the subject, the poem is simple.  It has only three stanzas of four lines each.  It uses a simple rhyme scheme the reinforces the simplicity of its subject, and creates a sense of peace, harmony, and escape.

Let us remember that imagery is defined as the creation of pictures through the use of words. The best imagery is created through the incorporation of as many of the five sense as possible into the poem, so that we not only see what the speaker is trying to describe, but can hear, smell, taste and feel it too. Note how we can see this in operation in the idyllic vision of the countryside given to us by the speaker:

And I shall have some peace there, for peace comes dropping slow,

Dropping from the veils of the morning to where the cricket sings;

There midnight's all a glimmer, and noon a purple glow,

And evening full of the linnet's wings.

The spectacular sight of morning, midnight and noon is described and at the same time we can "hear" the sound of the "linnet's wings" against this incredible backdrop. Such details help us to imagine the scene that is being described to us more vividly, and also link into the theme of the poem, which is the call that the speaker feels on his life to move to Innisfree and live in harmony with the nature. This is a call that, even in the greyest of city environments, he can hear.

The poem expresses the speaker's desire to escape from a fast-paced urban life characterized by "pavements grey." He longs instead for a slower-paced existence in nature. He dreams of escaping to a small island on a lake, where he would live alone in a simple house made of "clay and wattles." There he would grow nine rows of beans and have a beehive.

The speaker believes the slower-paced life he dreams of will bring him peace. He writes,

And I shall have some peace there, for peace comes dropping slow

He describes the calming rhythm of days and nights lived close to nature and the quiet lapping of the waves against the shore. The speaker retains an image of this simple life as he goes about his busy urban days:

I hear it in the deep heart’s core.

Since the time of the poet Hesiod, in 800 BCE, poets have expressed a longing for a less cluttered life and a belief that peace comes through living in harmony with nature. Yeats's poem is compelling in that his images capture the slow, simple pace of such an imagined life. The last line expresses the idea that one can find peace even amid the urban rush by imagining this simpler existence.

One of the best things about studying classic literature is that the themes found therein apply as much today as they did at the time of writing. So it is with Yeats's "The Lake Isle of Innisfree," a short but magnificent little narrative exploring the need many people feel to escape modern life and/or city life, and retreat to a place of solitude and quiet. The poem is heavily influenced by American writer Henry David Thoreau, who retreated to Walden Pond for a couple of years in the mid-1800's to do just what Yeats speaks of. Yeats envisions a cabin for himself, a place where he will hear water murmuring against the shoreline and not much else--sounds and images he imagines as he stands in the city on the concrete pavement.

Your question seems to be referring to another poem by Yeats, "The Stolen Child," which has the following refrain:

Come away, O human child!
To the waters and the wild
With a faery, hand in hand,
For the world's more full of weeping than you can understand.

Both "The Lake Isle of Innisfree" and "The Stolen Child" have some similarity. They suggest that escape from the real world is the best thing to do. There is a similar theme in Yeats' "Sailing to Byzantium." In that poem the speaker feels uncomfortable and alienated in his present surroundings and wishes to escape into the distance and into the past--or perhaps he only means that he wishes to escape mentally by losing himself in creative work.

It is easy for the modern urban dweller to understand and relate to these sentiments. Big cities at first seem attractive and exciting, but eventually they come to fell like expensive prisons full of lonely people who have been uprooted from nature and are leading lives of what Thoreau called "quiet desperation."