Let me repeat; this is of the very smallest importance in all the practical affairs of life, or indeed in relation to anything but philosophy and wide generalisations. But in philosophy it matters profoundly. If I order two new-laid eggs for breakfast, up come two unhatched but still unique avian individuals, and the chances are they serve my rude physiological purpose. I can afford to ignore the hens' eggs of the past that were not quite so nearly this sort of thing, and the hens' eggs of the future that will accumulate modification age by age; I can venture to ignore the rare chance of an abnormality in chemical composition and of any startling aberration in my physiological reaction; I can, with a confidence that is practically perfect, say with unqualified simplicity "two eggs," but not if my concern is not my morning's breakfast but the utmost possible truth.