Science is a recurring idea. It is prevalent throughout Donne's valediction, whether it be present in references to mathematical tools, such as a drawing compass, which was invented by Galileo only two years earlier, or to a circle and its infinite, perfect qualities. Science, too, is present as he references the "moving of th' earth," and that such movements, i.e., earthquakes, strike fear into the hearts of men. He also uses science to the spheres, meaning the Ptolemaic spheres in which the celestial bodies moved. Science plays a role, too, as Donne mentions that his love will expand "like gold to airy thinness beat," referencing both a precious metal and its physical properties.