Spencer's Theory of Universal Evolution.--A second meaning given to the word _evolution_ is that which Spencer popularized in his _First Principles_. This is a philosophical theory of the universe which asserts that not only have species of animals come to be what they are through a process of development, but everything whatsoever that exists, from molecules of matter to stars and planets. It is the view that the universe is in a process of development. Evolution in this wider sense includes all existing things whatsoever, while evolution in the sense of Darwin's theory is confined to the organic world. While the theory that all things existing have through a process of orderly change come to be what they are, is a very old one, yet it was undoubtedly Spencer's writings which popularized the theory, and to Spencer we also owe the attempt in his Synthetic Philosophy to trace the working of evolution in all the different realms of phenomena. The belief in universal evolution which Spencer popularized has also come to be generally accepted by scientific and philosophical thinkers. While Spencer's particular theories of evolution may not be accepted, some form of universal evolution is very generally believed in. The thought of evolution now dominates all the sciences,--physical, biological, psychological, and sociological. It is evident that the student of society, if he accepts fully the modern scientific spirit, must also assume evolution in this second or universal sense. The Different Phases of Universal Evolution.--It may be well, in order to correlate our knowledge of social evolution with knowledge in general, to note the different well-marked phases of universal evolution. (1) _Cosmic Evolution._ This is the phase the astronomer and the geologist are particularly interested in. It deals with the evolution of worlds. In this phase we are dealing merely with physical matter, and it is supposed that the active principle which works in this phase of evolution is the attraction of particles of matter for one another. This leads to the condensation of matter into suns and their planets, and the geological evolution of the earth, for example. Laplace's nebular hypothesis is an attempt to give an adequate statement of the cosmic phase of evolution. While this hypothesis has been much criticized of late, in its essentials it seems to stand. We are not, however, as students of society, concerned with this phase of evolution.