Nevada said:
I find it interesting that Crowley was such a rebel against established forms and yet so many that are interested in his deck want everyone to conform to what he says.
You will find that most 'Crowleyites', or most people who have time for him, live lives of non-conformity. So your opinion is not borne out in fact.
Crowley was a social rebel, but he was not a rebel against scholarship and learning: quite the opposite. He had no patience with dilettantes and he didn't make a deck for dabblers. If that's one thing that people who work with his material have in common, it is that attachment to scholarship and learning, and a commitment to learning about the magickal and Thelemic system, even the non-magickians and non-Thelemites among them (of which they are many). Rightly, they have no patience with those who can't even be bothered to read the Book of Thoth, let alone put in the time for inner and outer study to understand the symbolism and transform it into living keys.
Crowley also knew that in order to critique something - anything - one had to become proficient in it first. He was able to change a number of the GD and the original Thelemic tenets because he got to know them. He was able to synchretise so many different symbol-systems, because he understood them. By the same token, in order to critique him and to fly a different flag on his deck, we have to know his work. Simply to reject Crowley's writings on the grounds they are too obscure, difficult, complex, arcane, magickal or not one's cup of tea - that's not being a rebel, it's just lazy scholarship (btw, I'm not having a go at you, Nevada - you have engaged in the material despite finding it abstruse - and found as Aeon wrote, that it opens up to you with time - no doubt because of all the effort you put in knowing the deck. I am writing for those tempted to open the BoT, read three pages and put it down, never to open it again, and then say 'we don't need to read Crowley to work with his deck': to that statement, I say: nonsense.)
You don't have to be a Jew or a Christian to read the Bible: but you can't excise Jehovah from it. Likewise, you don't have to be a magickian or a Thelemite to read the Thoth tarot, but you can't excise its magickal intent and the specific Thelemic intent of the creators from it. I know at least two Thothites on this forum who are most definitely neither; and they are both among the most independent thinkers I know. But they are both committed to learning, and can't see how one is to illuminate the Book of Thoth (deck) from the inside without at the very least the Book of Thoth (book).
To answer the main thrust of this thread, Zan's question: you can study the Thoth without Crowley's writings, but that is incredibly time consuming, because it involves: 1) going back to all the sources used in over 40 years of magickal life; 2) figuring out the changes he made to the GD system, and why; and 3) figuring out the choices of symbols; getting to know 1940s Thelema from non-Crowley sources. Some elements on the cards are classic GD - for instance, most of the colours used, most, though not all, the astrological correspondences - but some are definitely not.
And just to throw a fly in the ointment, I'll add that reading only Crowley's material is equally worthless! You do need to go back to the source and figure out symbols from various perspectives, including your own dream-perspective (because you'll find, as you work with the Thoth, that its symbols will crop up in your dreams). Pathworking and working with the symbols as magickal keys are also two powerful ways of getting to know this deck. Of course, that's why studying the Thoth is like climbing a mountain - as soon as you think you're nearly at the top, you see another long hill looming above you.
When it comes to reading the deck, nobody - least of all Crowley - would expect you to have his books at your side at all times, slavishly trying to explain to your querents the alchemical process taking place in The Lovers, when what your querent wants to know is if their boyfriend will propose or not. From that perspective, the Book of Thoth (book) leaves the reader free to reach his own interpretations: with the caveat that fortune-telling is a worthless activity
As for Crowley's joke 'its perusal may be omitted with advantage' - I would say it's a tongue-in-cheek exercise in reverse psychology, of the kind he often practiced.