The Categorical Imperative is supposed to provide a way for us to evaluate moral actions and to make moral judgments. It is not a command to perform specific actions -- it does not say, follow the 10 commandments, or respect your elders.
A blurb on a book can be any combination of quotes from the work, the author, the publisher, reviewers or fans, a summary of the plot, a biography of the author or simply claims about the importance of the work.
The term plumb refers to a line that is perfectly vertical--in technical terms, an imaginary line that runs straight to the center of the earth. In construction, a framing member or building panel installed plumb will transfer its supporting load directly downward, giving it maximum load-bearing capacity.