In the third place, so far as bridging the chasm between the two orders of phenomena, it is not accomplished by the poetic intuition (to which we shall immediately refer), but by the human intellect, it seems legitimated by _analogy_. In our inductive interpretation of nature we perceive resemblances, and infer a likeness. 'Analogy is the soul of induction.' If, therefore, it be an illicit act of the reason which ventures to trace a parallel between nature and man, and interpret the former by the latter, how fares it with the foundations of human knowledge, and with the pillars of science herself? Is not all physical science the rational interpretation of nature? If we may not read the meaning of the great central force in the light of that force which we carry in the will, how can we warrantably interpret the laws of nature, in the light of that which we carry in the intellect? Are we not left in uncertainty as to the character of the entire fabric of our knowledge? The oracle is altogether dumb. If the way which seems to lead from the interior of the human will into the temple of outward nature be really a _cul-de-sac_, what warrant have we for opening a door on the other side, and walking down the avenues of positive science, imagining that in these pathways we shall find the only key to nature? To bring the analogy into effect, let us take two instances: the force with which I discharge a projectile and the force of gravitation. The former proceeds from the will, which is the originating power, though mechanical and physiological causes intervene. Since, therefore, similar effects have similar or resembling causes, it is a strictly analogical inference that as the effects correspond, the causes will resemble each other, and the essential part of the correspondence will not consist in the apparatus used (the phenomena), but in the will underlying, which is noumenal.[17]