This is one of my favorite books on Tarot. I originally read it 30 years ago, when it was first published in translation. It is, at first, very much a condensation of the musings of Papus in his "Tarot of the Bohemians". But, additionally, we have the speculations of an experienced Occultist & Freemason (Wirth was one of the founders of the Philalethes Society; the premier Masonic research organiation in the world). I try to read this book once every couple of years.
With this book, you must temporarily forget all the esoteric &/or Qabalistic attributes & correspondences you've already learned regarding Tarot. This book is a strong wind of fresh air, that will help you stay flexible regarding Tarot symbolism, as well as the Magicial implications and applications of these wonderful cards. Wirth is of the "Continental", Martinist schools (specifically the "Kabbalistic Order of the Rose Cross" of which he was very much a founder), following & layering upon the work of Eliphas Levi & Papus; thus his initial attributions are quite different from those with which most English-language readers would likely be familiar. Remember; if there were only one interpretation of the Tarot, it would be bound as a book, not a deck of individual cards/ideas.
An important note is that the B.O.T.A. Tarot of Paul Foster Case is a reconciliation between the the esotericism of Wirth with the symbolism of A.E. Waite.
Additional books to read in relation to this are:
Transcendental Magic, by Eliphas Levi (trans, A.E. Waite)
Tarot of the Bohemians, by Papus
The Sacred Tarot, by C.C. Zain