Initially Zaehner's reputation rested on his studies of Zoroastrianism , at first articles mostly on philology in academic journals. He labored for many years on a scholarly work, his Zurvan , a Zoroastrian dilemma (1955). This book provides an original discussions of an influential theological deviation from the Zoroastrian orthodoxy of ancient Persia's Achaemenid Empire , which was a stark, ethical dualism . Zurvanism was promoted by the Sasanian Empire (224-651) which arose later during Roman times. Until the Muslim conquest, Zurvanism in the Persian world became established and disestablished by turns.   
The Imperials category on our web site covers the majority of pens made by Sheaffer in the 1960s and 1970s, and some models were made into the 1990s. This category includes the explicitly "Imperial" named full size top of the line models such as the sterling 826 and 834, and the familiar crosshatch Imperial Sovereign. We have a few of the hard to find Imperial Is, as well as the Imperial II Deluxe and the Imperial III. Many of these models were made in both Touchdown and cartridge versions. We also lump a lot of what we call the "quasi-Imperial" models in this category, so this is where you will find the 300, 400 and 500 series pens from the 1970s -- the popular work horse 330s, 440s, 444s and 550s. Because of its very Imperial-y look, we also include the very collectible PFM (Pen for Men) in this category.