species.' As Wallace has himself said, 'This clearly pointed to
some kind of evolution ... but the _how_ was still a secret.'

This essay was published in the _Annals and Magazine of Natural History_
in September 1855. It attracted much attention from Lyell and Darwin and
later from Huxley. One important result of it was that Darwin and
Wallace entered into friendly correspondence. But although Darwin in his
letters to Wallace informed him that he had been engaged for a long time
in collecting facts which bore on the question of the origin of species,
he gave no hint of the theory of natural selection he had conceived
seventeen years before--indeed his friends Lyell and Hooker appear at
that time to have been the only persons, outside his family circle, whom
he had taken into his confidence.

In the spring of 1858, Wallace was at Ternate in the island of Celebes,
where he lay sick with fever, and as his thoughts wandered to the
ever-present problem of species, there suddenly recurred to his memory
the writings of Malthus, which he had read twelve years before. Then and
there, 'in a sudden flash of insight' the idea of natural selection
presented itself to his mind, and after a few hours' thought the chief
points were written down, and within a week the matter was 'copied on
thin letter-paper' and sent to Darwin by the next post, with a letter to
the following effect[113]. Wallace stated that the idea seemed new to
himself and he asked Darwin, if he also thought it new, to show it to
Lyell, who had taken so much interest in his former paper. Little did
Wallace think, in the absence of all knowledge on his part of Darwin's
own conclusions, what stir would be made by his paper when it arrived in
England!

Wallace's essay was entitled _On the Tendency of Varieties to depart
indefinitely from the Original Type_, and it is a singularly lucid and
striking presentment, in small compass, of the theory of Natural
Selection.

Had these two men been of less noble and generous nature, the history of
science might have been dishonoured by a painful discussion on a
question of priority. Fortunately we are not called upon for anything
like a judicial investigation of rival claims; for Darwin as soon as he
read the essay saw that--as Lyell had often warned him might be the
case--he was completely forestalled in the publication of his theory.
The letter and paper arrived at a sad time for Darwin--he was at the
moment very ill, there