Shakespeare used alliteration in several spots in the sonnet. "sessions of sweet silent thought" is one example, "Grieve at grievances" is another. He uses this literary device to give a rhyme apart from the structure. Also it might grab the attention to the reader and keep him attentive to the sonnet.
Shakespeare sets sort of a two tone atmosphere. for the first 3 groups are very sad and depressing atmosphere. but in the last 2 lines (couplet) the atmosphere changes to a feeling of acceptance and carelessness of everything that has happened "All losses are restored and sorrows end"(couplet). Atmosphere also helps get the reader to feel and better relate to the sonnet. This is shown through the diction he uses to express emotion. Words like woe, sad, grieve, and death.
Shakespeare creates a overarching theme or moral that can be taken from the poem. The moral is that whatever you may wish you had done or you had not done you should always have someone to confide in and find comfort in. This is shown by the couplet "But if the while I think on thee, dear friend, All losses are restored and sorrows end" (couplet).
Shakespeare makes great use of these literary device. He uses these devices to achieve his goal of displaying morals and themes. Shakespeare achieves his purpose by use of several different literary devices that appeal to the reader.
