If we be driven to a closer definition of the problem, if we be asked to explain with greater precision how these immaterial germs journey through space, we reply that we must guard against the mania for insisting on everything being explained. Absolute explanation is forbidden to the limit of our intelligence. We are forced to confess our powerlessness whenever we try to explain the phenomena of nature rigorously. What is the true cause of the fall of bodies, of the gravitation of the stars, of electricity, of heat? What is the cause of the circulation of our blood, of the beating of our hearts? The deepest obscurity veils the primary causes of these phenomena, which we all behold every day; and the more earnestly we desire to penetrate the secret essence, the more the darkness deepens in our minds. Since the time of Newton, the physicists have laid down a wise and excellent principle. They have agreed to study the laws of physical phenomena with sedulous care, to measure with exactness the effects of heat, weight, electricity, or light, but, also, never to disquiet themselves by researches into the causes of these phenomena. The more we learn, the further we advance in the knowledge of the universe and its laws, the more we become convinced that man knows absolutely nothing about first causes, that he ought to esteem himself happy in knowing the laws according to which the effects of these first causes manifest themselves; that is to say, the physical and vital actions which are visible to us, but that he ought, in the interests of his own peace of mind, to lay down a rule that he would never seek to know the wherefore of things. Pliny, speaking of first causes, said: "_Latent in majestate mundi_," ("They are hidden in the majesty of the world.") The thought is as fine as the phrase is eloquent. Let us, then, leave to nature her secrets, and, if we are led to believe that the sun sheds animated germs upon the earth and the planets, let us not try to penetrate further into the essence of this mysterious phenomenon. Let us not ask of the earth why she turns, the stone why it falls, the tree why it grows, our hearts why they beat--nor the rays of the sun why they produce life on earth, and immortality in the heavens. [Illustration] [Illustration] CHAPTER THE TWENTIETH. PRACTICAL RULES RESULTING FROM THE FACTS AND PRINCIPLES DEVELOPED IN THIS WORK.--THE ENNOBLING OF THE SOUL BY THE PRACTICE OF VIRTUE, BY SEEKING TO KNOW, THROUGH SCIENCE, NATURE AND ITS LAWS.--THE RENDERING OF PUBLIC WORSHIP TO THE DIVINITY.--THE MEMORY OF THE DEAD TO BE RETAINED.--WE OUGHT NOT TO FEAR DEATH.--DEATH IS ONLY AN UNFELT TRANSITION FROM ONE STATE TO ANOTHER, IT IS NOT A TERMINATION, BUT A METAMORPHOSIS.--THE IMPRESSIONS OF THE DYING.--THEY WHOM THE GODS LOVE DIE YOUNG.--REUNION WITH THOSE WHO HAVE GONE BEFORE.