=Survival-value.=--Every living thing and nearly every character or feature of a living thing that survives, survives because it has value or capacity for life--which may be called, in Professor Lloyd Morgan's phrase, _survival-value_. The character that gives an organism survival-value, or value for life, the character that enables it to fit its environment, may be of any order. The atom, as I have said elsewhere, is an organism writ small. The kinds of atoms that have survived in the age-long struggle for existence between atoms are those that have survival-value on account of their internal stability: as Empedocles argued ages ago. In the case of living things, which individually die, it is evident that the capacity to reproduce themselves is one of supreme survival-value. If mankind lost this capacity, all its other characters of survival-value, such as intelligence, would obviously avail it nought. Certain valuable members of society may fall short in this cardinal respect, and therefore become extinct. Indeed, other forms of survival-value, as we shall see, seem to be in large measure inimical to fertility: and this is perhaps the chief obstacle to eugenics.[11] Fertility apart, the character having survival-value may take a thousand forms. In the case of the parasitic microbe it is an evil character, the power to produce toxins or poisons. In the case of the tiger it is the possession of large and powerful bones and claws and muscles and teeth. In the case of the ox it is a complicated and efficient digestive apparatus, enabling it to fit into a food-environment which is too innutritious to sustain the life of creatures not so endowed. Nature seeks only the fittest; not the best but the best-adapted; she asks no moral questions. A Keats, a Spinoza, or a Schubert must go under if his factors of survival-value do not enable him to resist those of the tubercle bacillus, its toxins or poisons. She welcomes the parasitic tapeworm, all hooks and mouth or stomach, because these give it survival-value; and so on.