"Spring," for its first eight lines at least, is a praise-poem. Our speaker celebrates the beauty of nature and the profound effects it can have on man. The act of paying close attention to the natural world, and then allowing it to fill him with awe, seems to be of great importance to the speaker of this poem. The celebration of beauty is also closely linked with his contemplation of theology and the act of prayer.
Because the speaker's praise seems to be based on the fact that spring resembles the Garden of Eden and the what Christianity considers the original relationship between man and nature, the praise in this poem is really a lament for the fall of man and the fact that the initial perfection of Eden could not be maintained.
The natural world is very important to the speaker of "Spring" but, in a way, the importance of this spring landscape is really as an avenue for contemplating the biblical Garden of Eden and Christ's resurrection, and for experiencing a connection to God. By line 9 of the poem, the physical descriptions fall away, and the poem instead engages on a level of contemplation, questioning and prayer. It's as if the natural world provides a means of entering into an experience of God, and then our speaker moves on to a more direct interaction between himself and God.
Though many Christians often focus on the possibility of redemption after sin, the speaker of this poem appears wholly focused on the idea of keeping the innocent from sin in the first place, rather than redeeming them after their inevitable loss of innocence.
Hopkins singles out spring for description and praise, since he feels that it is the time of year that brings mankind closest to the harmony of man and nature (and God) that existed in the biblical Garden of Eden. We get the feeling that praising nature in its various earthly aspects is, for our speaker, also a way of praising God, the creator. Without nature, it seems, he could not get so close to God.
By not referring to an "I" in the poem, Hopkins steers the poem away from being about a single, personal experience, and makes it about a broader relationship between mankind and nature.
The natural imagery in "Spring," as well as the religious concerns surrounding the Garden of Eden, are centered on the idea of innocence. The loss of innocence – both in man's expulsion from Eden, and also currently, in children around the world – could be called the main fear or source of tension in the poem. Through the renewal of spring and its religious associations with the resurrection of Christ, there is also perhaps a hint of salvation from this seemingly inevitable loss.
Since all of our speaker's representations of innocence – spring, lambs, children – are temporary states (seasons change, lambs and children grow into adults), it is clear that, despite his prayer, our speaker knows that the loss of innocence is inevitable.