What does this quote mean: "Life's not a paragraph and death, I think, is no parenthesis."?

A paragraph is one linear group of sentences with a definite, immediately recognisable beginning and ending. A parenthesis is either or both the symbol ( or ). It is used to make a qualifying, explanatory or appositive remark, but its use isn’t that relevant here. Rather, the author is likely continuing the metaphor of life in terms of defined, clear starts and finishes. In other words, life isn’t (or is more than) a sequence of events happening one after another with a clear start and finish, and death is not the device that severs it. Another possible meaning is that life should not be looked at as the main event, and death not as a secondary point.