Quotes:Bacon, Roger
Zirkoff, Boris
Bacon, Roger (1214-1294). *De mirabili potestate artis et naturae, 1256-57, a work usually spoken of as Treatise on the Admirable Force of Art and of Nature. Transl. into English by L. Davis. Easton, Penna.: The Chemical Publ. Co., 1923.
Source: Boris de Zirkoff, «H. P. Blavatsky Collected Writings», vol. 11, p. 566