Quote of the day

Darwin, in a letter to J. D. Hooker (Dec. 12, 1856):

It is really laughable to see what different ideas are prominent in various naturalists' minds, when they speak of 'species': in some, resemblance is everything and descent of little weight -- in some resemblance seems to go for nothing, and Creation the reigning idea -- in some descent is the key, -- in some, sterility an unfailing test, with others it is not worth a farthing. It all comes, I believe, from trying to define the undefinable.