the great laws of creation?  Do they not teach us something of the system of nature?  If each species has been created independently, and without any necessary relation with pre-existing species, what do these rudiments, these apparent imperfections, mean?  There must be a cause for them; they must be the necessary result of some great natural law.  Now, if ... the great law which has regulated the peopling of the earth with animal and vegetable life is, that every change shall be gradual; that no new creature shall be formed widely different from anything before existing; that in this, as in everything else in nature, there shall be gradation and harmony—­then these rudimentary organs are necessary and are an essential part of the system of nature.  Ere the higher vertebrates were formed, for instance, many steps were required, and many organs had to undergo modifications from the rudimental condition in which only they had as yet existed....  Many more of these modifications should we behold, and more complete series of them, had we a view of all the forms which have ceased to live.  The great gaps that exist ... would be softened down by intermediate groups, and the whole organic world would be seen to be an unbroken and harmonious system.

The article, in which we can see a great generalisation struggling to be born, ends thus: 

It has now been shown, though most briefly and imperfectly, how the law that “every species has come into existence coincident both in time and space with a pre-existing closely allied species,” connects together and renders intelligible a vast number of independent and hitherto unexplained facts.  The natural system of arrangement of organic beings, their geographical distribution, their geological sequence, the phenomena of representative and substituted groups in all their modifications, and the most singular peculiarities of anatomical structure, are all explained and illustrated by it, in perfect accordance with the vast mass of facts which the researches of modern naturalists have brought together, and, it is believed, not materially opposed to any of them.  It also claims a superiority over previous hypotheses, on the ground that it not merely explains but necessitates what exists.  Granted the law, and many of the most important facts in nature could not have been otherwise, but are almost as necessary deductions from it as are the elliptic orbits of the planets from the law of gravitation.

Some time after the appearance of this article, Wallace was informed by his friend and agent, Mr. Stevens, that several naturalists had expressed regret that he was “theorising,” when what “was wanted was to collect more facts.”  Apart from this the only recognition which reached him in his remote solitude was a remark in an approving letter from Darwin (see p. 129).

As Wallace wrote nothing further of importance until the second essay which more fully disclosed his view of the origin of species, we will now briefly trace the growth of the theory of Natural Selection up to 1858, as it came to Darwin.