A memoir is an account of facts and experiences about the life of an individual. The word memoir comes from the french "mémoire" which means "memory". Memoirs are narratives usually told from the first-person point of view (the author is the protagonist) telling us about an experience that makes the reader reflect upon a speific theme.
Memoirs have a couple of main elements that are essential, these are: Narrative (it is told as if it was a story), Truth (but it contains factual and true information), Voice (first person point of view), Theme (they focus on a specific theme or part of the life of a person, not on the whole life), Answers (it reflects upon action and asks questions so than then answers can be provided).
In the excerpt from Ozymandias by Percy Shelley, the below lines show that art alone can last forever.
Half sunk, a shattered visage lies, whose frown, And wrinkled lip, and sneer of cold command.
Tell that its sculptor well those passions read Which yet survive, stamped on these lifeless things"
The above line is the one that makes us understand that art can last alone forever. Percy Shelley talks about the sculpture's face that lies shattered.
Still, it cannot be forgotten to mention that, the frown, the wrinkled lip and the sneer of the command the face has cannot be missed to be appreciated.
Having understood these passions well, the poet says that the sculptor's accurate and artistic depictions still lives.