What was it then that led to the victory of the one idea over the other?  The cause was intellectual.  With the experts, it was logical conviction:  one set of ideas was found to fit the facts somewhat better than the other set of ideas.  With men in general the intellectual change came more slowly and in a different way:  they adopted or imitated the ideas of those who knew.  It was therefore not natural selection at all which led to the presence and power of the one idea rather than the other in the minds of thoughtful men.  One idea was deliberately accepted and the other deliberately rejected.  The former was accepted on grounds of which the most general account would be, if we may use the term, to call them subjective.  But natural selection is a physical, external, objective process.  It is carried out without the individual’s volition:  he is not aiming at the end.  It is simply natural law which, with many varieties of living beings before it, exterminates the unfit individuals.  Thus nature in its own blind way produces a result of the same kind as that which the will of man would bring about by subjective selection.

The origin of this term ‘natural selection’ is overlooked when people talk glibly about ‘natural selection’ of ideas.  Darwin used the term ‘natural selection’ because he thought he saw an analogy between the tendency of nature and the selective purposes of intelligent beings.  It was because nature, working without intelligence, produced the same kind of result as man does by intelligent selection, that he ventured to use this term ‘selection’ of the process of nature.  Perhaps he was hardly justified in adopting the term, as nature does not select; she only passes by.  At the same time, artificial selection also includes, although it is not limited to, this negative or weeding-out process.  When you select a certain plant for growth in your garden you weed out the neighbouring plants which encroach upon it, so as to give it a chance to grow and thrive.  By removing its competitors, you let air and light surround the plant, and it spreads its leaves to the sun.  The healthy growth which results is due to the removal of obstacles by an external power; and it is in this way—­by the removal of obstacles—­that natural selection works.

Intelligent or artificial selection is not restricted to this negative method of working; and its operation, positive as well as negative, was certainly well known long before Darwin’s day.  Starting with the familiar facts of artificial or purposive selection, Darwin showed how results similar to those aimed at and reached in this way might be brought about by the operation of certain natural laws, working without purpose or design.  Purposive selection pursues its ends more directly and in general attains them far more quickly than does natural selection.  A still more striking characteristic is the fact that it does not entail the waste and pain which mark the course of natural selection.  Witness the records