  A relation between shear and dielectric spectra is derived for highly viscous
liquids with a small rotational contribution $\Delta\epsilon$ to the dielectric
constant. It is valid if the shear fluctuations and the electric dipole
fluctuations have the same spectrum. The comparison to literature data, taken
under carefully controlled conditions to ensure samples from the same charge
and the same temperature control in both measurements, indicates that the
relation may be fulfilled or not depending on the substance. The connection to
recent work on strong correlations is discussed.
