It is clear that the poet has changed a lot during the five year gap since he last visited Tintern Abbey in terms of how he responds to nature and what he thinks about it. If we look at the poem carefully we see that Wordsworth describes how, on his first visit, his response to the beauties of nature was much more passionate and emotional that it is now. Note how he himself describes his intial reaction to the scene that he revists now:
The sounding cataract
Haunted me like a passion: the tall rock,
The mountain, and the deep and gloomy wood,
Their colours and their forms, were then to me
Nature thus was something that invoked a supremely passionate response in the poet, and was like an appetite in the way that he is described as not being able to get enough of the joys of nature.
In contrast, his reaction now seems to be far more philosophical and mature. The poet says that he has exchanged the "aching joys" and "dizzy raptures" of five years ago with the ability to look upon nature and hear "The still, sad music of humanity" that somehow gives Wordsworth a transcendent experience that allows him to see nature as "The anchor of my purest thoughts" and the "soul / Of all my moral being." This poem points towards the way that Wordsworth has been able to mature in his response to nature, and now that he looks upon this same momentous view, nature to him represents a much more transcendent experience that directs Wordsworth's soul and outloook in life.