First Principles of Theosophy
http://api.ning.com/files/vGOdtPwwDjVo3JeYr7ala8wTfjb0Wh2MpVkcmp*atYxFgrfQAyvizCT22E2ehEh0*gHW*KPGLqZkdFdSIMCJ2sRnJyZiQehN/THEFIRSTPRINCIPLESOFTHEOSOPHY.pdf
By C. Jinarajadasa, a former president of the Theosophical Society. A thoroughgoing explanation of Theosophical concepts, with lots of useful diagrams for those who appreciate graphic presentations of complex information. Puts it all together.