The unjustified conception of "life," or "living," or being "alive," and not dead, as necessarily a state of incessant chemical and other change, is bound up with the old fancy that life is not to be considered as a state or motion of a special and complex structure called protoplasm, but is a thing, a spirit or an essence, which takes possession of organic bodies and makes them "live." According to Sir Oliver Lodge, if chemists could build up the chemical materials which constitute protoplasm, the protoplasm so made by them would not live. It would (he stated at the meeting of the British Association in Birmingham in 1912) have to receive a charge or infusion, as it were, of this thing suggested by the word "life." It cannot live itself (according to the suppositions of Sir Oliver), but serves as the vehicle, the receptacle, for this supposed intangible entity "life." In the same imaginative vein, our grandfathers used to say that heat was due to the entity or "fairy" "caloric" which could be enticed into or driven from material bodies, making them "hot" by its presence and cold by its greater or less exclusion. The suspended animation of frozen germs and their return to life when warmed could thus be represented as an affection or affinity between the fairy "Vitalis" and the fairy "Caloric," the former fleeing from the body and waiting near when the latter deserts his place, but returning to happy union with "Caloric" when he again, however feebly, pervades once more the vehicle provided for "Vitalis." Such imaginary essences are not of any assistance to us in arriving at a knowledge of the facts, and so far from helping us to a comprehension of the ultimate nature of things (which we have no reason to suppose that it is possible for us to attain) their introduction tends to the substitution of imaginary causes and unverified assumptions for the carefully-tested and demonstrated conclusions of science.