Amongst Cagliostro's personal effects, when arrested by the Catholic Church in 1789, the Inquisition found a peculiar seal bearing the symbol of a snake pierced by an arrow and holding an apple in its mouth. The letters L (followed by 3 dots in a triangular formation) P (followed by 3 dots…) D (followed by 3 dots…) were engraved upon it. The three dots arranged in the triangular form are considered to represent the triune God dwelling in Heaven. The practice began in 1774 by the Grand Orient of France; Masons who used the symbol as a “period” after their initials were often referred to as “Three Point Brothers”. It is still used by Masons in the US, particularly those of the Scottish Rite, although the meaning is not always recognized.
Cagliostro himself described the cipher to the Inquisition interrogators:
...the serpent with the apple in its mouth, which I have adopted for my crest, and which denotes the cause of original sin, and of the subsequent fall. The redemption of our Lord Jesus Christ, is the arrow which has pierced the serpent; and this we ought to keep constantly before our eyes and in our hearts.
(Extract from The Masonic Magician, Watkins 2008)
Eliphas Levi also commented upon Cagliostro's Seal in his book - History of Magic, 1860
As explained by the cabalistic letters of the names Acharat and Althotas, it expresses the chief characteristics of the Great Arcanum and the Great Work. It is a serpent pierced by an arrow, thus representing the letter Aleph, an image of the union between active and passive, spirit and life, will and light. The arrow is that of the antique Apollo, while the serpent is the python of fable, the green dragon of Hermetic philosophy. The letter Aleph represents equilibrated unity. This pentacle is reproduced under various forms in the talismans of old magic...The arrow signifies the active principle, will, magical action, the coagulation of the dissolvent, the fixation of the volatile by projection and the penetration of the earth by fire. The union of the two (the serpent and arrow) is the universal balance, the Great Arcanum, the Great Work, the equilibrium of Joachin and Boaz. The initials LPD, which accompany this figure, signify Liberty, Power, Duty; also Light, Proportion, Density; and Law, Principle, Right. The Freemasons have changed the order of these initials, and in the form of LDP they render them as Liberté de Penser, Liberty of Thought, inscribing these on a symbolical bridge; but for those who are not initiated they substitute Liberté de Passer, Liberty of Passage. In the records of the prosecution of Cagliostro it is said that the examination elicited another meaning as follows: Lilia destrue pedibus : Trample the lilies under foot; and in support of this version may be cited a Masonic medal of the sixteenth or the seventeenth century, depicting a branch of lilies severed by a sword, having these words on the exergue: Talem dabit ultio messem – Revenge shall give this harvest.
Cagliostro - Healer, Alchemist and Freemason - Talk presented to Barron Barnett Lodge of Research 146 UGLQ, 18 March 2015