Shelley calls on night to come quickly: "Swiftly walk o'er the western wave, / Spirit of Night." All day long he has waited for night; day has lingered like an unwanted guest. Neither death nor sleep will serve as a substitute. Death will come too soon in any case and sleep will come when night is over. Neither can give what night can give.
As in "Ode to the West Wind," "The Cloud," and "To a Skylark," Shelley uses myth-making as his device for apostrophizing night This device enables him to give life and personality to a natural phenomenon.
The poem was written in 1821, a year before Shelley's death. Like other lyrics of Shelley's last years, it reflects depression and a kind of weary resignation. It is not a cheerful poem, but, on the other hand, it does not incorporate a death wish like his "Stanzas Written in Dejection" of December 1818. Shelley explicitly rejects death in the poem. Yet the poem has a touch of morbidity in it: Night is preferred to day, and it is not invoked so that with it will come sleep. Shelley wants to escape from day and seek refuge in night, but in the poem he doesn't tell us why he wants night to come.
The raison d'être of this strange little poem probably lies in Shelley's personality and in his state of mind when he wrote the poem. People found Shelley friendly and sociable, but he preferred the company of books and his own thoughts to society. During the day, he found it impossible to avoid the company of others; there was no escaping the many demands on his time and energy. At night, when others were sleeping, Shelley could withdraw into his own private world to read and meditate as he pleased. Night brought rest and peace, freedom from society and the everyday demands of life, and also the opportunity to indulge in the dark thoughts that the frequently unsatisfactory circumstances of his life made inevitable. One of these unsatisfactory circumstances in 1821 was that he had become infatuated with a young Italian girl, Emilia Viviani. His wife, Mary, was by this time well acquainted with Shelley's propensity to be strongly attracted to young women in whom he felt he detected certain affinities to be found nowhere else, and she had learned to be tolerant. But inevitably tensions developed, for Mary realized that she could not be everything for Shelley that he required. In September of 1821, Emilia married, and Shelley, who had idealized her in his "Epipsychidion," was cut off from all further communication with her. Her marriage left him, as he wrote to his friend John Gisborne, "in a sort of morbid quietness." The Emilia episode was the major source of emotional tumult in Shelley's life in 1821.
"To Night" is so personal a poem that it is unlikely that it owes anything to poems with a night setting such as Milton's "Il Penseroso nor to the eighteenth-century "Graveyard School of Poetry," which preferred night to day as a time for serious meditation. "To Night" is probably to be linked with other poems written in 1821, such as the moving "A Lament":
O World! O life! O time!
On whose last steps I climb,
Trembling at that where I had stood before;
When will return the glory of your prime?
No more — Oh, never more!
Out of the day and night
A joy has taken flight:
Fresh spring, and summer, and winter hoar,
Move my faint heart with grief, but with delight
No more — Oh, never more!