Herbert Spencer first undertook the great task of discovering the unifying principle of nature. He recognized all possible phenomena as parts of one great whole, and held that all were united by natural law. He differed from Comte in that he recognized the imperceptible as a reality, but made no attempt to explain it or to bring it into harmony with the phenomena of sense, but designated it the unknowable. He divided his system into two general divisions--the knowable, which includes all things of sense, experience, and the unknowable, which includes everything else, or the invisible and imperceptible. He held the knowable is the proper sphere of man's knowledge or philosophy, and the unknowable the legitimate domain of God and religion. And while he held that God and religion were imperceptible and unknowable, he held they were none the less a truth of the highest degree of certainty. It is therefore well said that all who fear the downfall of religion as a result of the encroachments of science or philosophy may thank Herbert Spencer for placing it where neither science or philosophy can touch it. Upon the law of relativity he places the basis of that which can be known, and that which cannot be known. He says: "We think in relations. This is truly the form of all thought.... On analyzing the process of thought we found that cognition of the absolute--the unknowable--was impossible because it presents neither relations nor its elements--difference and likeness. Further we found that not only intelligence but life itself consists in the establishment of internal relations in correspondence with external relations. And lastly, it was shown by the relativity of our thought we are eternally debarred from knowing or conceiving absolute being, yet that this relativity of our thought necessitates that vague consciousness of Absolute Being which no mental effort can suppress." It is apparent that these propositions contradict each other. For, if from the relativity of thought we are eternally debarred from knowing or conceiving Absolute Being, how is it that we have a vague consciousness of this same Absolute Being which cannot be suppressed? Consciousness is one form of knowledge. Spencer, thus recognizing the reality of the unknowable, regards that which is or can be known as different manifestations of the unknowable.