physiologus

Müller in the conviction _psychologus nemo nisi physiologus_, he was the first in Great Britain during the 19th century to apply physiology in a thoroughgoing fashion to the elucidation of mental states.

Encyclopaedia Britannica, 11th Edition, Volume 3, Part 1, Slice 2 "Baconthorpe" to "Bankruptcy" Various

"Physiologus" is not the original title; it was given to the book because the author introduces his stories from natural history with the phrase: "the physiologus says", that is, the naturalist says, the natural philosophers, the authorities for natural history say.

The Catholic Encyclopedia, Volume 12: Philip II-Reuss 1840-1916 1913