Paul Foster Case (1884-1954) was one of the most respected of the American occultists in the early 20th century. "An Introduction to the Study of Tarot" was originally published in 1920 and has been a leading introductory guide for all with an interest in the Tarot.
From the book: This book aims to show how to use the Tarot cards for the purpose of evoking thought, and thus bringing to the surface of the student's consciousness those great, fundamental principles of Occult Science which lie hidden in the hearts of all mankind. All these principles are based upon a single truth, and knowledge of that truth is innate in every human being; but not until it has been found and brought into the light of consciousness is it available for use. Hence the portals of ancient temples bore the motto, “Know Thyself;” hence Jesus said, “Seek first the kingdom of God, which is within you;” and Eckhartshausen declared: “As infinity in numbers loses itself in the unit which is their basis, and as the innumerable rays of a circle, are united in a single center, so it is also with the Mysteries; their hieroglyphics and infinitude of emblems have the object of exemplifying but one single truth. He who knows this has found the key to understand everything, and all at once.”