A power of consciously reasoning

James Sully, « Mental Evolution in Animals », Nature a Weekly Illustrated Journal of Science, vol. 29, Londres, MacMillan, 1884, p .333

And while it is no doubt difficult as the author remarks (p. 191), to attribute to an animal so low down in the scale as the larva of the caddice fly a power of consciously reasoning, it seems, on the other hand, hard to understand how, by the mere play of natural selection unaided by any rudiment of conscious discrimination and adaptation of means to ends, this little creature could have acquired the habit of either lightening its floating case by attaching a leaf to it or weighting it by attaching a small stone according as it becomes too heavy or too light.