"Unconscious Memory" was largely written to show the relation of Butler's views to Hering's, and contains an exquisitely written translation of the Address. Hering does, indeed, anticipate Butler, and that in language far more suitable to the persuasion of the scientific public. It contains a subsidiary hypothesis that memory has for its mechanism special vibrations of the protoplasm, and the acquired capacity to respond to such vibrations once felt upon their repetition. 

I do not think that the theory gains anything by the introduction of this even as a mere formal hypothesis; and there is no evidence for its being anything more. Butler, however, gives it a warm, nay, enthusiastic, reception in Chapter V (Introduction to Professor Hering's lecture), and in his notes to the translation of the Address, which bulks so large in this book, but points out that he was "not committed to this hypothesis, though inclined to accept it on a prima facie view." Later on, as we shall see, he attached more importance to it.

The Hering Address is followed in "Unconscious Memory" by translations of selected passages from Von Hartmann's "Philosophy of the Unconscious," and annotations to explain the difference from this personification of "The Unconscious" as a mighty all-ruling, all- creating personality, and his own scientific recognition of the great part played by UNCONSCIOUS PROCESSES in the region of mind and memory.

These are the essentials of the book as a contribution to biological philosophy. The closing chapters contain a lucid statement of objections to his theory as they might be put by a rigid necessitarian, and a refutation of that interpretation as applied to human action.