Every failure will only prove a stimulus to renewed exertion, as every discovered path of error leads one step in advance toward the path of truth, and that in turn to harmony with the Book of ALL TRUTH. CHAPTER II. THEORIES OF ORGANIC LIFE. After inquiring into their _order_ of succession, the _relation_ which organic fossils have to each other, as genera and species, falls naturally to be considered. How have these various families of creatures, brought to light by geology, been formed? In what manner have they become extinct? Have they all proceeded from a few original types, which have been modified by circumstances, increased in variety, and perfected in form, as they advance from the older to the newer formations? And does geology furnish any data on which to build a theory of their extinction as the higher and succeeding kinds emerged into being? A learned author, Professor Pictet of Geneva, has spoken of these speculations in terms of a rule or law, as follows:—“_The faunas of the most ancient formations are made up of the less perfectly organized animals, and the degree of perfection increases as we approach the more recent epochs._” This was long held as a favorite dogma among geologists, when, in proportion to the scantiness of facts, there was an increasing eagerness to magnify their value, and to build upon them the widest generalizations. But now, since accurate observations are more and more multiplied, and the principles of palæontology are better understood, the doctrine of a gradual advance of animal organization toward higher and more perfect forms as we ascend through the successive deposits of the earth’s crust, is daily losing ground among the cultivators of the science. The notion is based upon the theory of _a scale of beings_, in which all animals are supposed to form a series, or to constitute links of an unbroken chain, whereof each species is more perfect than that which precedes it, and the varying degrees of perfection constantly increasing until they reach their maximum in man, the highest link in the chain. M. Pictet himself regards this theory as vague and unsupported by facts, as well in the organization of the extinct as of the existing races of animals. These beings, he says, are divided into a certain number of groups, each of which exhibits a peculiar type; but while some of the groups are manifestly superior to others when we consider their organization generally, it happens also that the result of a comparison sometimes fails to establish any real superiority. The faunas of the more ancient formations he holds to be far less imperfect than has been often supposed, where the vertebrate type is represented by the fishes, and whose structure is as complicated and finished as the most recent of their kind; while the invertebrate again furnishes numerous examples of fossilized gasteropoda and cephalopoda, the most perfect orders of the molluscous class.