From Sass and Compass in Action, by Wynn Netherland, Nathan Weizenbaum, Chris Eppstein, and Brandon Mathis:
1.3 What is Compass?
Compass helps Sass authors write smarter stylesheets and empowers a community
of designers and developers to create and share powerful frameworks. Put simply,
Compass is a Sass framework, designed to make the work of styling the web
smooth and efficient. Much like Rails as a web application framework for Ruby,
Compass is a collection of helpful tools and battle-tested best practices for Sass.
(emphasis added)