I must have expressed myself atrociously: I meant to say exactly the reverse of what you have understood. F. Jenkin argued in the _North British Review_ against single variations being perpetuated, and has convinced me, though not in quite so broad a manner as here put. I always thought individual differences more important; but I was blind, and thought that single variations might be preserved much oftener than I now see is possible or probable. I mentioned this in my former note merely because I believed that you had come to a similar conclusion, and I like much to be in accord with you. I believe I was mainly deceived by single variations offering such simple illustrations, as when man selects [i.e. isolates][34]. [34] _Life and Letters_, vol. iii. pp. 157-8. Again, somewhere about the same time, he wrote to Moritz Wagner:-- Although I saw the effects of isolation in the case of islands and mountain-ranges, and knew of a few instances of rivers, yet the greater number of your facts were quite unknown to me. I now see that, from the want of knowledge, I did not make nearly sufficient use of the views which you advocate[35]. [35] _Ibid._ pp. 157-8. Now it would be easy to show the justice of these self-criticisms by quoting longer passages from earlier editions of the _Origin of Species_; but as this, in view of the above passages, is unnecessary, we may next pass on to another point.