The phrase "bliss of solitude" appears in the final stanza of "I Wandered Lonely as a Cloud." Wordsworth writes that "They flash upon that inward eye/Which is the bliss of solitude." The "they" the line refers to are the golden daffodils alongside the lake that appear in the first stanza of the poem. 

In his "Preface to Lyrical Ballads," Wordsworth discusses "emotion recollected in tranquillity." The daffodils represent the source of this type of emotion, as the poet recalls them as he lies alone upon his couch in a state of contemplation. The Romantics, including Wordsworth, believed that nature was the source of a great emotional response in individuals. By enjoying the "bliss of solitude," or the quiet contemplation that allows people to think about and understand their emotions, individuals can arrive at a state of transcendence. This is the "bliss" that Wordsworth refers to. Only by contemplating beauty and the sensations that nature produces in private can individuals have this type of transcendent experience. 

The phrase "the bliss of solitude" appears in the fourth and final stanza of William Wordsworth's poem "I Wandered Lonely as a Cloud" (also sometimes referred to as "The Daffodils"). The first three stanzas of the poem recount Wordsworth's joy in seeing a field of "golden daffodils" along a lake on one of his many walks through England's Lake District. The fourth stanza answers the question which closes the third stanza: "What wealth the show to me had brought." In other words, Wordsworth wonders what redeeming quality the flowers may have for him. He acknowledges in the last stanza that when he is alone "in pensive mood" the daffodils "flash upon that inward eye/ Which is the bliss of solitude." That "inward eye" is most certainly the poet's soul or spiritual vision, and when he is alone the thought of the daffodils makes for a unique and extremely pleasurable feeling. It is in this quiet and solitary time that Wordsworth seems to understand the true beauty of the physical world deep down in his spirit as he figuratively "dances with the daffodils."