For a quick overview of the teachings: click here
In the modern Theosophical movement the word "Theosophy" has been used with several different meanings:
a) It is frequently used to describe the body of teachings that were given through Mme. Blavatsky and other Theosophical writers. This body of knowledge is frequently called "modern Theosophy" (with capital T).
b) It is also used to refer to the universal Ancient Wisdom underlying all religions, which can be found at their core when they are stripped of accretions, deletions, and superstitions. This is sometimes referred to as "ancient" or "timeless" theosophy.
For the purpose of the Theosophical Society and its members it could be said: Theosophy, a recapitulation of the ancient wisdom tradition, is a body of teachings and doctrines, having consistency with that disseminated by the founders of the modern Theosophical Movement, explanatory of Universal Laws; Laws that establish the principle of Unity inherent in Nature and which are the basis of Universal Brotherhood. Pablo Sender, however, in his article, What is Theosophy?, (The Theosophist Dec 2007) go to article comments; "Since the Theosophical Society was not founded to promote any particular system, its members should not limit Theosophy to a definite set of concepts, if they do not want to create a new cult. It is our responsibility to preserve a space of freedom for every member to discover universal theosophy by himself so that, by living according to its teachings, he or she may realize the theosophical state of consciousness."
The article gives the following classification to make a distinction among the different applications of the term theosophy/Theosophy:
a) theosophia : the transcendental theosophy, that is, the state of consciousness of inner enlightenment.
b) universal theosophy : those theosophical teachings given by every great thinker, sage, and philosopher, modern or ancient. In this category we may add two subcategories:
b1) ancient theosophy, sometimes called the Ancient Wisdom, meaning that ancient truth known in the past as the ‘Wisdom-Religion’.
b2) modern Theosophy (with capital T), the Theosophical teachings offered by members of the Theosophical Society.
What Is Theosophy? - And What it is Not. Geoffrey Farthing 1971
Why Study Theosophy? - Geoffrey Farthing 1999
What is Theosophy? - Pablo Sender. Originally published 2007
What is Theosophy? - H.P. Blavatsky. Originally published 1879
What should Theosophical Groups Study? - John Algeo. Originally published 2007