I agree Mike that Decker's argument is unconvincing. While Etteilla frequently uses the term 'cabalistic', there are few places in which he makes direct reference to Hebrew. The largest reference is probably his use of the ShemHamforash (72 names), which as far as I can tell however he doesn't connect with the Tarot but is related to other services he offered (e.g., discovering the name of one's Genie, the making of talismans) and which he presents mainly from their appropriation into astrological lore. There is one brief note however in which he directly refers to the Hebrew names of God as true hieroglyphs - which I make a minor note here only in relation to the Gates of Light being an exegesis of the names of God associated with each sefiroth. In a note at the bottom of p.73 of his Theoretical and Practical lessons from the Book of Thoth:mikeh wrote: In fact, as I found by producing a searchable version of "Gates of Light" on my computer, at least one of the "Etteilla" keywords for most of the number cards can be found in almost every chapter of the book, and so relating to almost every sefira. The "correspondences" are just too numerous to be meaningful.
Occasionally none of the keywords occurs in the relevant chapter of Gates of Light, for example Etteilla"s keyword "critique" (which Decker translates as "crisis") for the 8 of Swords. In that case, Decker blithely substitutes a vaguely related word that does occur in the right chapter of Gikatilla, e.g. in this case "jealousy". These substitute words are invariably common biblical words found in many chapters of Gikatilla's book.
It may be possible to save Decker's thesis in some other way by reference to Cabalist works, or other esoteric writings available in the 18th century . It is at this point only clear that his arguments as they stand are quite inadequate.
(1) Reflechiffez,, je vous prie, si les noms de Dieu en caracteres hebraiques, ne sont pas de vrais hyerogliphes.
(1) Consider, I pray you, if the names of God in Hebrew characters are not true hieroglyphs.
(Etteilla makes use of the term cabalistic, in relation to Tarot, as combining letters, numbers and hieroglyphs. However, this brief note is the only place, that I have found so far, in which Etteilla comes close to a direct comparison of the hieroglyphs of the tarot as cabalistic letters with Hebrew characters.)
No doubt some would be delighted by the frequent reference to 'Choens' throughout this text, and treat it as proof positive that Etteilla was a member of the Elus Coens! ;)