Yet if there is no difference in essential nature between one kind of energy and another, there does appear a marked difference when we come to consider them in relation to particular results of their operation. Let us take an example. We explain that classic instance of gravitation, the fall of an apple, by reference to the law formulated by Newton which extends to every particle of matter in the visible universe. But we also find that the fall of the apple is, for apples, a necessity of life; if the seed did not fall to the ground when ripe there would be no more apple trees. Yet gravitation acts quite indifferently to the life of the apple. Whether the branches overhang a river, or a street, or a plot of fertile ground, the apple will fall straight towards the centre of the earth. The fulfilment, therefore, of the vital needs of the apple is plainly a by-product of the force of gravitation. In this relation, gravity has no directive or psychic element. Yet in larger relations, we have to take note of the fact that if there were no such thing as gravity, there would be no apples and no earth. Thus the law of gravitation is a condition of life as we now know it. The fact that it acts mechanically, without selection or purpose, in relation to particular occurrences is quite consistent with the view that it, or the conditions of the ether from which it possibly arises, may be directive and psychic in relation to life as a whole, or rather to what we recognize as the manifestation of life in the material universe. We have now got hold of a valid distinction between mechanical and directive agencies. We can distinguish them not by their nature but in relation to the particular phenomenon we are considering. We call them mechanical where that phenomenon is a by-product of the agency, and directive where, if the agency were conscious, we should say that this was its main intent. I can see no more fundamental distinction. It follows from this that the same action can be at once both mechanical (physico-chemical) and directive. The old distinction between vital and mechanical energy disappears. The question resolves itself simply into that of the number of distinct agencies which are deemed necessary to account for the universe.