In this column, we continue our explanation of Maxwell’s equations, the seminal classical explanation of electricity and magnetism (and, ultimately, light). For those of you new to the series, consider finding the last few appearances of this column to get caught up. Alternately, you should be able to find past columns on our website, www.spectroscopymag.com and look for “The Baseline” link. Words of warning: for my own reasons, the figures are being numbered sequentially through this series of columns, which is why the first figure in this column is numbered 26. Also, we’re going to get a bit mathematical. Unfortunately or otherwise, that’s par for the course.