Part III of Volume I, the Addenda on Occult and Modern Science, is by the assessment of careful sympathetic readers like Joscelyn Godwin and Wouter Hanegraaff the most intellectually interesting stretch of The Secret Doctrine. The Addenda were added because, as Blavatsky says here, Western Theosophists studying the Stanzas had found them in apparent conflict with then-current scientific understanding. Her response is not to retract or to soften but to argue that the apparent conflict points to a deeper problem in nineteenth-century materialism itself. The seventeen sections that follow constitute a sustained engagement with the cutting-edge physics, chemistry, and biology of 1888 — Newton, Faraday, Maxwell, Tyndall, Crookes, Lord Kelvin (Sir William Thomson), G. A. Hirn, J. B. Stallo, the philosophers of science of her moment. She is doing comparative philosophy of science avant la lettre. Whether or not her positive proposals (Fohat, akasha, vital force) are correct, the negative critique of late-Victorian mechanistic reductionism is sharper than is sometimes credited, and several of the conceptual problems she presses on (action-at-a-distance, the nature of ether, the inadequacy of the atomic hypothesis as then understood) were genuinely unresolved and would not stay unresolved for long.Editor