This sentence is based on an old proverb, the source of which is unknown and the author cannot trace it back. There is no evidence that Shelley said it at present.
Because this sentence is full of philosophy, many people have quoted it, but it is not original.
Data expansion:
About the author: percy bysshe shelley (English original name: percy bysshe shelley, August 4th, 1792- July 8th, 1822), a famous British writer and romantic poet, is regarded as one of the best English poets in history. British romantic democratic poet, the first socialist poet, novelist, philosopher, essayist and political writer, reformer, Platonist and idealist, was deeply influenced by utopian socialism.
Masterpieces: Prometheus Liberated, ode to the west wind and Ode to a Lark.
Baidu encyclopedia _ Shelley