Besides [these same naturalists continue], the greater part of the fossil bones that have been assembled and compared are those of animals different from any of the species actually known; has the kingdom of life therefore changed? This one cannot refuse to believe.[659] As Nature proceeds unceasingly from the simple to the composite, it is probable that the most imperfect animals should have been created before the tribes, higher in the scale of life. It even seems that each of the animal classes indicates a sort of suspension in the creative power, an intermission, an era of repose, during which Nature prepared in silence the germs of life which should come to light in the course of the cycles. One might thus enumerate the epochs of living Nature, epochs remote in the night of ages and which have been obliged to precede the formation of mankind. A time may have been when the insect, the shell, the unclean reptile, did not recognize the master in the Universe and were placed at the head of the organized bodies.[660] These observers add: It is certain that most perfect beings come from less perfect, and that they are obliged to be perfected in the sequence of generations. All animals tend towards man; all vegetables aspire to animality; minerals seek to draw nearer to the vegetable.… It is evident that Nature, having created a series of plants and animals, and having stopped at man who forms the superior extremity, has assembled in him all the vital faculties that it had distributed among the inferior races.[661] These are the ideas of Leibnitz. This celebrated man had said: “Men hold to animals; these to plants, and those to fossils. It is necessary that all the natural orders form only one sole chain, in which the different classes hold strictly as if they were its links.”[662] Several philosophers have adopted them,[663] but none have expressed them with more order and energy than the author of the article _Nature_, in _Le Nouveau Dictionnaire d’Histoire naturelle_.