have no knowledge of the Creator. Thus we must begin an inquiry into the universe systematically, such as we have learned from the trend of rational inference. It is also evident that this aim is to be attained by the investigation of one part of the universe after another, and that help must be derived from predecessors, as is the case in other sciences. Imagine that the science of geometry and astronomy had become extinct in our day, and a single individual desired to find out by himself the magnitude of the heavenly bodies, their forms, and their distances from one another. Even though he were the most sagacious of men, it would be as impossible for him as to ascertain the proportion of the sun and the earth and the magnitude of the other stars. It would only be attainable by aid of divine revelation, or something like it. If it be said to him that the sun is a hundred and fifty or sixty times as big as the earthy he would take it to be sheer mad-
