Nature presents herself in a great variety of beings, according to classes and species, which, while disinct from each other, work together, and for each other, but are not transformed one into the other. Modern Natural Philosophy has ventured upon the bold step to examine the mystery, how beings of a higher order could grow out from those of a lower species; how higher organisms gradually developed themselves from the most inferior. Whether it will succeed to penetrate also into that mystery — whether such a transformation of one from another shall prove to be truth, is the office of naturalists to decide in the present or in future. But this much we see, that species do exist, that they do not change one into another, that they are and remain distinct from each other. The same Power which at the beginning created them — as is asserted, one out of the other — should necessarily continue the same process, should even this day create an animal from a plant and continuously perfect it to its higher organism. But the present world presents no such process; on the contrary, every species remains within its fixed limits, it continually begets individual beings of its own kind, but is not changed into another. Hence it is not a promoting, but ordering power that creates and preserves every kind in its individuality; not one that is blindly rushing forward without stopping, but which preserves nature as a whole, composed of different parts, so that it is unchangeable both as a whole and in its variety. Nature is arranged according to a fixed will, according to an independently ruling reason, and is preserved in this arrangement: the Universe is one system, held together by its great variety, composed of different parts, and yet forming one harmonious whole. This is wisdom, judicious and systematical order, so that even destructive powers present themselves as creative elements, producing new, nobler creations. This is the work of self-conscious Reason, — not that of a power propelling without a certain object in view. It is a bold word which an astronomer once uttered when he presented his work on astronomy to his monarch. The latter being astonished not to find God mentioned in the book, the former observed: ‘I need not that hypothesis.’ It is true, it was not necessary for him, in his explanation of the laws and their working, at the same time to state how they grew into existence, and who had fixed them everlasting and unchangeable; but what a man of profession may leave untouched, that a thinking man cannot avoid, he must seek a higher cause which creates according to rational principles.
-Abraham Geiger (Founder of Reform Judaism), Judaism and its History, Lecture I: Of the Nature of Religion, pp. 8-10