§ 42. The class of phenomena to be considered under the title of Evolution, is in a great measure coextensive with the class commonly indicated by the word Progress. But the word Progress is here inappropriate, for several reasons. To specify these reasons will perhaps be the best way of showing what is to be understood by Evolution.

In the first place, the current conception of Progress is shifting and indefinite. Sometimes it comprehends little more than simple growth—as of a nation in the number of its members and the extent of territory over which it has spread. At other times it has reference to quantity of material products—as when the advance of agriculture and manufactures is the topic. Now the superior quality of these products is contemplated; and then the new or improved appliances by which they are produced. When, again, we speak of moral or intellectual progress, we refer to the state of the individual or people exhibiting it; while, when the progress of Knowledge, of Science, of Art, is commented upon, we have in view certain abstract results of human thought and action. In the second place, besides being more or less vague, the ordinary idea of Progress is in great measure erroneous. It takes in not so much the reality as its accompaniments—not so much the substance as the shadow.