The most acknowledged work of Percy Bysshe Shelley titled 'A Defence of Poetry' proposes that 'human emotions constantly change with their experiences in life' and thus, he believed that poetry must possess the ability to bring this change(to inspire and transform the reader). This idea is clearly reflected in the above lines of 'Mutability' i.e. 'we feel...cares away.'
These lines portray that human emotions constantly vary with their experiences as good experiences bring 'joy and laughter' while the sad encounters evoke 'weep or sorrow.' It suggests one can choose to either 'embrace' the 'woes' or let it go away. Thus, this collaboration of distinct emotions implies that human emotions vary with time and experiences faced by humans throughout their life.
