# response to magnetic field is smaller than electric field?

I'm reading a paper, which just explain an another approach to derive Fresnel's equation. (https://aapt.scitation.org/doi/pdf/10.1119/1.15551?class=pdf)

At one point, it says

One naturally asks why the magnetic Brewster's angle is not well known, given that its "domain" is just as large as that of the Brewster's angle. The answer lies in the asymmetry of nature: There are no magnetic charges. The consequence of this asymmetry is that responses of macroscopic systems to magnetic fields, coming from moving electric charges, are smaller by v/c effects.

I confess that I'm not sure what the 'v/c effect' means even though I studied both undergrad/grad E&M. I assume that it refers to something like $$\vec{E}+\vec{v}/c\times\vec{B}$$,(in gaussian unit. I guess the paper was written when gaussian were dominating.) but I learned that it's just the problem of notation, and E and B are quite symmetric, i.e. wave energy is stored equally in electric/magnetic field. (like in Why are magnetic fields so much weaker than electric? ) I know that magnetic field is always dipole or higher order while electric field can begin with monopole, but that has no relation with v/c, isn't it?

Can someone clarify this for me please?