The Prelude is a long poem by William Wordsworth compiled into fourteen books. All these books trace his spiritual growth with the subtitle of the poem itself as its the theme, which is the growth of the poet's mind.
The title stands justified as Wordsworth describes how Nature began its mysterious work in his conscious and subconscious mind. He is convinced that there are hidden forces in Nature impacting him inadvertently right from the time he was a young boy and he thus, recounts a few incidents and comments upon their significance in shaping up his mind. The poem is often considered as the poet's spiritual autobiography in which he not only makes an attentive observation of the "misty mountains" and the "solitary vales" but also feels their influence on him.
Apart from showing us the role of Nature in the growth of an individual, the poet also related his experiences to bring out the change in perceptions based on emotions. Nature is a guide, friend, philosopher, nurse, playmate, mother and what not! She is both beautiful and stern, fearful and sublime, inspirational and also intimidating. There is also a sense of hope in the form of philosophical optimism that the poem offers.
Innocence and simplicity are suggested by the Romantic idea of going back to one's childhood and by arriving at the essential attribute viz. The "Vital Soul". Nature is a throbbing presence in the poem which suggests the poet's mysticism, spiritual outlook, and pantheism. It is not a religious poem at all as nowhere the poet talks about Christ, but it is spiritual, a step higher than religious.
The poem is written in Blank Verse, unrhymed lines of iambic pentameter with trochees and anapaests. It is quite verbose and bathetic with blatant repetition. Nature imagery prevails throughout with certain obscure classical references. Despite being quite lengthy, the poem offers a wonderful reading as Nature forms a cosmic order of which material world is one manifestation and the moral world is another.