It is plain that we might here enter our dissent from Haeckel's method, for he requires us, before we can proceed a single step in the evolution of man, to assume many things which he cannot prove. What evidence is there, for example, of the possibility of the development of the rational and moral nature of man from the intelligence and the instinct of the lower animals, or of the necessary dependence of the phenomena of mind on the structure of brain-cells? The evidence, so far as it goes, seems to tend the other way. What proof is there of the spontaneous evolution of living forms from inorganic matter? Experiment so far negatives the possibility of this. Even if we give Haeckel, to begin with, a single living cell or granule of protoplasm, we know that this protoplasm must have been produced by the agency of a living vegetable cell previously existing; and we have no proof that it can be produced in any other way. Again, what particle of evidence have we that the atoms or the energy of an incandescent fire-mist have in them anything of the power or potency of life? We must grant the monist all these postulates as pure matters of faith, before he can begin his demonstration; and, as none of them are axiomatic truths, it is evident that so far he is simply a believer in the dogmas of a philosophic creed, and in this respect weak as other men whom he affects to despise. We may here place over against his authority that of another eminent physiologist, of more philosophic mind, Dr. Carpenter, who has recently said: "As a physiologist I must fully recognize the fact that the physical force exerted by the body of man is not generated _de novo_ by his will, but is derived directly from the oxidation of the constituents of his food. But, holding it as equally certain--because the fact is capable of verification by every one as often as he chooses to make the experiment--that in the performance of every volitional movement physical force is put in action, directed, and controlled by the individual personality or _ego_, I deem it as absurd and illogical to affirm that there is no place for a God in nature, originating, directing, and controlling its forces by his will, as it would be to assert that there is no place in man's body for his conscious mind." Taking Haeckel on his own ground, as above defined, we may next inquire as to the method which he employs in working out his argument. This may be referred to three leading modes of treatment, which, as they are somewhat diverse from those ordinarily familiar to logicians and are extensively used by evolutionists, deserve some illustration, more especially as Haeckel is a master in their use.