30. Ever since there have been schools of philosophy, these points have been disputed; and it is probable they always will be; but it is to very little purpose. We know the existence of the corporeal world, we know its relations to ourselves, we know its properties and its laws, so far as they are subject to our observation; but its intrinsic nature is beyond the reach of our senses, or our instruments. Increased acuteness of observation and improvement in the power and delicacy of instruments, discovers new mysteries, and man finds the barriers which he believed the _ne plus ultra_, removed from him as he advances. Will he ever be able to pass them? Will he ever make the entire circuit of this scientific world? Is the knowledge of the intrinsic nature of the subject of this infinity of phenomena which astonish us, reserved to the future? It is hard to believe it. The telescope, becoming more perfect, extends the limits of the universe, and seems to behold the infinitely great; the perfection of the microscope, advancing in the opposite direction, regards the infinitely little. Where are the limits? It is probable that man is not permitted to reach them while in this world. The mind of man in its fruitful activity, struggles alternately after the two extremes, but just as he flatters himself he is reaching the last limit, he feels that something stronger than himself withholds him from attaining the object of his noble desires; it is the chain that binds him to the mortal body, and obstructs the flight of his pure spirit. CHAPTER VI. SUBSTANTIALITY OF THE HUMAN ME. 31. We have not found perfect unity in corporeal substances: all that are subject to our senses may be resolved into a number of others equally substances in their turn; a body is rather an aggregate of substances, than one substance. We do not find the unity in the bodies; we attribute it to them either inasmuch as they form a common link of our sensations, or inasmuch as we consider the different substances subordinated to one being and governing substance. Thus the parts of an animated body constitute a sort of unity, inasmuch as they are subordinate to the principle which animates them.