This ferret reference is an obscure one...
 
John Maddox Roberts wrote the SPQR mystery series set in the dying days of
the Roman Republic (c. 70 - 60 B.C.).  His sleuth, Decius Caecilius
Metellus, constantly refers to his ability to ferret out information about
various murders and conspiracies.  But the best ferret line is in the third
book in the series, _The Sacrilege_ in which he says:
 
"It seemed to me that my guardian *genius*, my ferret-muse, hovered near
and was aiding me at untying this knot of murder and intrigue."
 
The four books in the series are, unfortunately, out-of-print, but if you
like historical mysteries that are heavy on conspiracy and intrigue, that
describe many strange elements of Roman culture, and that make wonderfully
acerbic comments about Roman politics and social mores, you should look for
this series in used book stores.  The four titles, all published by Avon in
paperback, are:
 
SPQR
SPQR II: The Catiline Conspiracy
The Sacrilege: An SPQR Mystery
The Temple of the Muses: An SPQR Mystery
 
Cheryl (and the spirits of Hooligan and Circe)
[Posted in FML issue 2068]