3. We come, lastly, to the notions or ideas of IMMENSITY and ETERNITY, and we ask, Are these necessary ideas of the reason, or can they be confounded with the relations of co-existence and succession on the one hand, or with the attributes of finite extension and duration on the other? This is not a mere question of systems of philosophy or theology--it is a question of facts. Are the ideas of Absolute Infinity and Eternity necessary intuitions of the reason? The world of sense-perception, the world of science, is phenomenal and contingent. All that is offered to our observation is _limited_ and _temporal_. The universe surrendered to our science is one of quantities and quantitative relations. It is conditioned by number and form. Its extensions, spaces, and motions are capable of admeasurement. Its worlds and systems are subject to numeration. The phenomena of the universe are all subject to change, they have beginning, succession, and end. But beyond the notions of the limited and the temporal, we find in consciousness the ideas of the _illimitable_ and the _eternal_; the latter always appearing to reason as the necessary correlates of the former. The finite necessarily supposes the infinite; the temporal necessarily supposes the eternal. The two classes of notions are essentially different, and defy all attempts to generalize them under higher concepts. The infinite is not the totality of finite existences; eternity is not the prolongation of finite durations. Immensity and eternity are absolutely and unconditionally necessary ideas. I can easily conceive the non-existence of any finite thing. I can, without any contradiction, suppose the whole world to be destroyed. All which has a derived and a dependent existence may cease to be. But we can not conceive the source of all existence annihilated. There is one notion which it is impossible for me to annihilate in thought, and that is the notion of absolute being--underived, unconditioned, changeless, eternal being. Despite the destruction of all determinate extension and all finite duration, there remains a Supreme Reality, unlimited, unbeginning, and endless, as an absolute necessity of thought. Here, then, are two absolute ideas found in the depths of consciousness--the ideas of IMMENSITY and ETERNITY; ideas as real, as natural, and as necessary as the notions of extension and duration. Immensity and Eternity are attributes of God. Extension and Duration are attributes of finite, dependent existence. Space and time are relations between co-existing things and successive events.