The central theme of this poem is that there is a “veil of forgetfulness” between our previous existence and our present life since birth—“Our birth is but a sleep and a forgetting.”  The way Wordsworth explains this separation is that just after birth, during early childhood, we still recall the joy and wonder of the place we came from (, “Heaven lies about us in our infancy”) but that gradually “Earth fills her lap with pleasures of her own” and, like a nurse or nanny, “doth all she can/ To make her foster child, her Inmate Man,/Forget the glories he hath known”.  The poem goes on to poetically describe the growing and maturing process , the making of plans (the metaphor is of a builder or architect planning and building his life), until maturity (“The years to bring the inevitable yoke”); the Romantic point of view now comes into focus in the poem, when “in our embers/Is something that does live/That nature yet remembers”.  In other words, the multiple beauties of Nature (“calm weather”, “immortal sea”, “Fountains, Meadows, Hills, and Groves”, the “splendor in the grass” etc. remind us of the beauty of the “heaven” we left when we were born into this world,  so that in our old age we are again reassured that Nature “hath kept watch o’er man’s mortality".  Every stanza, every line of this ode explains the seemingly enigmatic statement at the beginning: “The child is father of the man.”