Nevertheless, however conservative we may be, and however much alive to the folly and wickedness of tampering with settled convictions-no matter what they are-without sufficient cause, there is yet such a constant though gradual change in our surroundings as necessitates corresponding modification in our ideas, desires, and actions. We may think that we should like to find ourselves always in the same surroundings as our ancestors, so that we might be guided at every touch and turn by the experience of our race, and be saved from all self-communing or interpretation of oracular responses uttered by the facts around us. Yet the facts will change their utterances in spite of us; and we, too, change with age and ages in spite of ourselves, so as to see the facts around us as perhaps even more changed than they actually are. It has been said, "Tempora mutantur nos et mutamur in illis." The passage would have been no less true if it had stood, "Nos mutamur et tempora mutantur in nobis." Whether the organism or the surroundings began changing first is a matter of such small moment that the two may be left to fight it out between themselves; but, whichever view is taken, the fact will remain that whenever the relations between the organism and its surroundings have been changed, the organism must either succeed in putting the surroundings into harmony with itself, or itself into harmony with the surroundings; or must be made so uncomfortable as to be unable to remember itself as subjected to any such difficulties, and therefore to die through inability to recognise [sic] its own identity further. Under these circumstances, organism must act in one or other of these two ways: it must either change slowly and continuously with the surroundings, paying cash for everything, meeting the smallest change with a corresponding modification so far as is found convenient; or it must put off change as long as possible, and then make larger and more sweeping changes. Both these courses are the same in principle, the difference being only one of scale, and the one being a miniature of the other, as a ripple is an Atlantic wave in little; both have their advantages and disadvantages, so that most organisms will take the one course for one set of things and the other for another. They will deal promptly with things which they can get at easily, and which lie more upon the surface; those, however, which are more troublesome to reach, and lie deeper, will be handled upon more cataclysmic principles, being allowed longer periods of repose followed by short periods of greater activity.