the monistic or mechanical (causal) conception of the universe. In opposition to the dualistic or teleological conception of nature, our theory considers organic as well as inorganic bodies to be the necessary products of natural forces. It does not see in every individual species of animal and plant the embodied thought of a personal Creator, but the expression for the time being of a mechanical process of development of matter, the expression of a necessarily active cause, that is, of a mechanical cause (causa efficiens). Where teleological Dualism seeks the arbitrary thoughts of a capricious Creator in miracles of creation, causal Monism finds in the process of development the necessary effects of eternal immutable laws of nature." Haeckel's "Anthropogeny" also is replete with attacks upon a teleological {162} view of nature, which leave nothing wanting in distinctness and coarseness. On page 111, Vol. I, we read: "The rudimentary organs clearly prove that the mechanical, or monistic conception of the nature of organisms is alone correct, and that the prevailing teleological, or dualistic method of accounting for them is entirely false. The very ancient fable of the all-wise plan according to which 'the Creator's hand has ordained all things with wisdom and understanding,' the empty phrase about the purposive 'plan of structure' of organisms is in this way completely disproved. Stronger arguments can hardly be furnished against the customary teleology, or Doctrine of Design, than the fact that all more highly developed organisms possess such rudimentary organs." (Compare also Vol. II, p. 439: "The rudimentary organs are among the most overwhelming proofs against the prevailing teleological ideas of creation.") According to his opinion (Vol. I. p. 245), comparative anatomy may no longer look for a "pre-arranged plan of construction by the Creator." Besides, he calls it an anthropocentric error to look upon man as a preconceived aim of creation and a true final purpose of terrestrial life; and on page 17, of Vol. II, he supports this judgment by comparing the relative shortness of the existence of mankind with the length of the preceding geological periods: "Since the awakening of the human consciousness, human vanity and human arrogance have delighted in regarding Man as the real main-purpose and end of all earthly life, and as the centre of terrestrial Nature, for whose use and service all the activities of the rest of creation were from the first defined or predestined by a 'wise providence.' How utterly baseless these {163} presumptuous anthropocentric conceptions are, nothing could evince more strikingly than a comparison of the duration of the Anthropozoic or Quaternary Epoch with that of the preceding Epochs." And on page 234, Vol. II: "Hence it is that, in accordance with the received teleological view, it has been customary to admire the so-called 'wisdom of the Creator' and the 'purposive