The common conviction of our race that the universe had a beginning, that it has been the subject of great catastrophal changes, and that it will finally come to an end, is not to be regarded as an insignificant fact. As Herbert Spencer justly remarks, "We must presume that beliefs that have long existed and have been widely diffused ... beliefs that are perennial and universal ... have some foundation, and some amount of verity."[134] Universal beliefs must rest on some common ground. That common ground can not be experience. A belief which was as clearly and confidently held four thousand years ago as it is held to-day can not have been gradually attained by successive generalizations. It is grounded on the fundamental antithesis between Becoming and Being, phenomena and reality, the changeful and the permanent, the finite and the infinite, the temporal and the eternal, which has been a necessary form of thought to all minds in all ages. The human mind has never been able to conceive these contradictory opposites as predicable of the same subject. The universe as presented to sense is a perpetual genesis, a ceaseless change; therefore it can not be permanent. It is a time-march of phenomena; therefore it can not be eternal. It is limited by quantity and quantitative relations; therefore it can not be infinite. Thus reason has always conceived the universe as having a _beginning_, and has confidently predicted that it will come to an _end_. All systems of philosophy, and, indeed, many systems of religion, have been attempts to explain "the beginning or origin of things"--that is, they have been "_à priori_ theories of the universe."[135] Even Atheism itself comes under this definition: it is an attempt to explain the origin of the universe and of man on the _à priori_ assumption of the self-existence of Matter, Space, and Motion. Thus all systems of thought, ancient and modern, have had their birth in the innate conviction that there is something to be explained, and that human reason is adequate to the task of furnishing an explanation. They all assume that the universe had a beginning, and their one, central problem is, "How are we to conceive aright the origin of things?"