Life" (1910), of an over-ruling God, of the spiritual nature of man, and
of the other world of spiritual beings.

An essay that excited special attention was that on Mimicry. The two on
Birds' Nests brought forth some rather heated correspondence from
amateur naturalists, to which Wallace replied either by adducing
confirmation of the facts stated, or by thanking them for the
information they had given him.

With reference to the paper on Mimicry, it is interesting to note that
the hypothesis therein adopted was first suggested by H.W. Bates,
Wallace's friend and fellow-traveller in South America. The essay under
this title dealt with the subject in a most fascinating manner, and was
probably the first to arouse widespread interest in this aspect of
natural science.

The next eight years saw the production of many important and valuable
works, amongst which the "Geographical Distribution of Animals" (1876)
occupies the chief place. This work, though perhaps the least known to
the average reader, was considered by Wallace to be the most important
scientific work he ever attempted. From references in letters written
during his stay in the Malay Archipelago, it is clear that the subject
had a strong attraction for him, and formed a special branch of study
and observation many years before he began to work it out systematically
in writing. His decision to write the book was the outcome of a
suggestion made to him by Prof. A. Newton and Dr. Sclater about 1872. In
addition to having already expressed his general views on this subject
in various papers and articles, he had, after careful consideration,
come to adopt Dr. Sclater's division of the earth's surface into six
great zoological regions, which he found equally applicable to birds,