The harvesting of truth is a safe enough enterprise, but the devouring of error is a more dangerous pastime, since flames are liable to spread beyond our control; and though, in a world overgrown with weeds and refuse, the cleansing influence of fire is a necessity, it would be cruel to apply the same agency again at a later stage, when a fresh young crop is springing up in the cleared ground. CHAPTER V RELIGION AND PHILOSOPHY The aphorism sometimes encountered, that "whatever properties appertain to a whole must essentially belong to the parts of which it is composed," is a fallacy. A property can be possessed by an aggregation of atoms which no atom possesses in the slightest degree. Those who think otherwise are unacquainted with mathematical laws other than simple proportion or some continuous or additive functions; they are not aware of discontinuities; they are not experienced in critical values, above which certain conditions obtain, while below them there is suddenly nothing. To refute them an instance must suffice:— A meteoric stone may seem to differ from a planet only in size, but the difference in size involves also many other differences, notably the fact that the larger body can attract and hold to itself an atmosphere—a circumstance of the utmost importance to the existence of life on its surface. In order, however, that a planet may by gravitative attraction control the roving atoms of gas, and confine their excursions to within a certain range of itself, it must have a very considerable mass. The earth is big enough to do it; the moon is not. By simply piling atoms or stones together into a mighty mass there comes a critical point at which an atmosphere becomes possible; and directly an atmosphere exists, all manner of phenomena may spring into existence, which without it were quite impossible. So, also, it may be said that a sun differs from a dark planet only in size; for it is just the fact of great size which enables its gravitative-shrinkage and earthquake-subsidence to generate an immense quantity of heat and to maintain the mass for æons at an excessively high temperature, thereby fitting it to become the centre of light and life to a number of worlds. The blaze of the sun is a property which is the outcome of its great mass. A small permanent sun is an impossibility. Wherefore, properties can be possessed by an aggregate or assemblage of particles which in the particles themselves did not in the slightest degree exist.