Rosicrucian Esotericism, a lecture Cycle by Rudolf Steiner given June 3 - 12, 1909 contained in the german volume (GA (CW) 109/111). Chronologically the latter half of The Principle of Spiritual Economy Single German Volume.
For your convenience, below is a zip file of this entire set of lectures. It does require that you have an unzipping utility of some kind on your computer. For you mac people this is built in.
The Entire Book Rosicrucian Esotericism
Lecture 1: Rocicrucian Esotericism
Lecture 2: Soul in the World around Us
Lecture 3: The Nature and Being of Man
Lecture 4: Man Between Death and Rebirth
Lecture 5: The Physical World as an Expression of Spiritual Forces and Beings
Lecture 6: The Configuration and Metamorphosis of Man's Physical Body
Lecture 7: Evolutionary Stages of our Earth before the Lemurian Epoch
Lecture 8: Stages in the Evolution of our Earth. Lemurian, Atlantean, Post-Atlantean Epochs