Essay published in 1615, in response to enquiries of Christina of Tuscany, as quoted in "Aspects of Western Civilization : Problems and Sources in History" by Perry McAdow Rogers, (p. 53), sourcebooks.fordham.edu. 1988.
Richard Watson, Thomas Taylor, Thomas Raffles, Francis Augustus Cox, Andrew Fuller (1826). “The Christian library: A reprint of popular religious works”, p.539