the ordinary scientific argument from experience, and, although not strictly logical, is an expression of the conviction, common to every student of Nature, of the continuity and permanence of physical law. This conviction is not supported by arguments, but is built up slowly and surely by the daily observation of Nature’s working and of the never-failing fulfillment of her laws. Our author's reasoning, therefore, is calculated rather to convince the man of science than the mere logician.
Having established this principle, he goes on to state the converse, that matter is never annihilated. For, he argues, since nothing can be created, a continual unreplaced loss would have been going on, which in the infinite course of past time would have left nothing of the universe at all. Here, again, he shows that he has the scientific conviction of the uniformity of nature. An objector might have said, “Though there has been no loss, no annihilation in time past, how do you know that there will be none in time future?” This argument, though unanswerable, is incapable of producing conviction in a scientific mind. Such an argument, as Tyndall remarks in his “Fragments of Science,” is employed by the spiritualists in regard to the sun's failing to rise on the morrow. “Before such a state of mind,” says he, “the scientific intellect is absolutely powerless.” The convictions that rise from uniform experience in the pursuit of physical studies are unassailable by any reasoning short of a mathematical demonstration.
Lucretius adds that, in many cases of apparent annihilation, matter is but lost to grow again in another form. He instances the rain whose drops fall upon the ground and are scattered, but appear again in the blooming tree which shelters beneath its branches flocks and herds and the race of men. Here, as often with this poet, a beautiful episode crops out in the midst of his philosophical argument. Indeed, it is one of his characteristics, and forms his claim to be considered a great poet, that, combined with his appreciation of the order and continuity of nature, he has a fervent love for all its aspects of beauty and life. Often he turns aside to tell of frisking lambs and babbling brooks, and trees that spread their branches far and wide. He seems to have loved nature in all its forms, and to have devoted to it all the wealth of his intellect and imagination. He closes this argument with the celebrated saying, “Nature builds up one thing by means of another, and suffers nothing to be born except another die.”
These two propositions, that nothing is created and nothing destroyed, are the primary postulates upon which as a foundation he builds the whole theory of atoms. His first step is to show that there are bodies, which, though invisible, are yet appreciable through the senses. The air, he argues, must consist of solid particles in as true a sense as water, for water itself can not produce greater effects than violent winds. There are, too, other particles of matter which affect
