Through his sister Dorothy, he sees what he was before. He has a pantheistic belief, that God is manifesting eminent throughout. For Wordsworth, nature now includes music, a sense of tragedy. There is a fundamental harmony that interfuses and penetrates everything. It impels the thinker and objects of one's perception.
Nature ultimately acts as a guide and the soul of all moral being.
Hence, nature is one's anchor of his purest thoughts and is, therefore, maternal and a sense of spirituality.