"Thus the thread which was spun in darkness by those who sought a perpetual motion has conducted us to a universal law of nature, which radiates light into the distant nights of the beginning and of the end of the history of the universe. To our own race it permits a long but not an endless existence; it threatens it with a day of judgment, the dawn of which is still happily obscured. As each of us singly must endure the thought of his death, the race must endure the same. But above the forms of life gone by, the human race has higher moral problems before it, the bearer of which it is, and in the completion of which it fulfils its destiny." Helmholtz, _Popular Lectures on Scientific Subjects_, p. 191, seq. The distinguished German had just before observed, "Even though the force store of our planetary system is so immensely great ... still the inexorable laws of mechanics indicate that this store of force, which can only suffer loss and not gain, must be finally exhausted." On the subject of such vast cosmical changes, the reader may like to peruse the remarks of _Littré_ in his most recent volume--"Les choses, ou, pour mieux dire, nos choses sont d'hier, dût cet hier comporter de prodigieuses durées. "Cette nouveauté est un témoignage que notre monde, notre univers, auront une fin. Ce qui a commencé doit finir, la raison le dit, et toutes nos connaissances physiques le confirment. Le soleil et les étoiles se refroidissent incessamment, versant dans les espaces une chaleur qui ne leur revient jamais. Quelque chauds qu'ils soient, ils le sont chaque jour un peu moins, le calorique s'y épuisera; ils s'éteindront, comme déjà leurs planètes se sont éteintes. Que deviendront ces masses animées d'un mouvement rapide? Nul ne peut le dire. Mais il suffirait d'un choc entre elles pour y transformer un prodigieux mouvement en une prodigieuse incandescence, et y renouveler un cycle de chaleur et d'expansion. "Ce serait se perdre en vaines et gratuites hypothèses, que de spéculer sur ce que deviendra notre univers quand il aura pris fin, comme de spéculer sur ce qu'il fut avant qu'il eût pris commencement." Littré, _La Science_, pp. 560, 1. There are thinkers who believe that these cycles, immeasurable to Man, took their governing laws from a supreme Designer. They will be aided by Helmholtz and Littré in shaping their ideas of His far-reaching wisdom and power. There are also thinkers who find within their own inward Being a consciousness of kinship with the Source of Causation, so infinitely beyond cycles apparently infinite. How great then the value of human Spirits bearing His likeness, and with it a promise of surviving the period when our world's cycles shall vanish away in Space--to be replaced by other hereditary cycles, or to be remembered no more for ever!