“Huc referunt aliqui speculum Pythagorae cujus meminit Agrippa in _Retractat. de Magia_, cap. _de Prestigiis_, qui sanguine perscripsisse dicitur, quae collibuisset, in speculo et eo ad Lunam obverso, commonstrasse res exaratas stanti a tergo in disco Lunae. Hoc si verum est, utique non naturaliter contingit sed ope Daemonis.”
In the same work, par. i., p. 438-440, is a discussion of the proposition: “Utrum in lunari disco aliquid legendum exhiberi potest arte catoptrographica.” He says that Baptista Porta maintained this in his Natural Magic (cap. xvii., lib. 17). He also quotes from the _Philosophia Occulta_ of Cornelius Agrippa (lib. i., cap. 6) as follows:
“Si litteras parabolico speculo inscripseris idque tempori plenilunii Lunae exposueris eae litterae ceu in vasto quodam speculo impressae reflexaeque ubilibet locorum legi poterunt. Ita Pythagoram aiunt, dum Hydrunti moraretur, litteras Lunae inscriptas Constantinopoli amicis legendas dedisse.”
There is also a passage in Dr. Thomas Browne’s _Pseudodoxia Epidemica_ (Vulgar Errours), p. 60 (Edition of 1650), in reference to this myth: “Which is a way of intelligence very strange; and would requite the Art of Pythagoras; who could read a reverse in the Moon.”
Other references in occult literature to the alleged mirror of Pythagoras are as follows:
ATHANASIUS KIRCHER. _Ars Magna Lucis et Umbrae_ (Cryptologia, cap. i.) (Romae, 1646, fol.), p. 908. (Quotes from Cornelius Agrippa and Porta, and denounces the account as absurd, and against natural possibility.)
BUBALUS. _Commentationem de Angelis_ (Lugduni, 1622, fol.), 9-50, art. 1, quaesito 2, difficult. 2, § 3, pp. 64-66. (Combats views of Paracelsus.)
PARACELSUS. _Magia_, lib. 5, de Speculi constitutione. (Distinguishes five kinds of alleged magic mirrors; none of them, however, having any optical significance.)
BOISSARDUS. _Tractatus de Divinatione_ (Oppenheim, 1616, folio), p. 297.
(_ii._) AULUS GELLIUS. Carus Sterne (_Gartenlaube_, 1877) and Ayrton (_Journal Royal Institution_, 1879) refer to Aulus Gellius as having written of mirrors which “sometimes reflected their backs and sometimes did not.” The reference appears to be a mistaken one; for all I have been able to find in Aulus Gellius is the following passage in the _Noctes Atticæ_, bk. xvi., ch. xviii. (which is upon that branch of Geometry called [Greek: optikê]):