creation or construction, when we undertake to deal with matter and its properties, are so imperfect, and that which constitutes living organisms is so utterly beyond our reach, that we do not sufficiently remember how entirely it is within the compass of the infinite Power, which has given to matter all the properties that it possesses and has living organisms under its absolute control, to form a system of construction and operation for beings of entirely distinct characters, carrying it through each of them in parallel lines, or causing it to diverge into varying results with an economy that neither wastes the constructive power nor fails to exert it where it is needed. To argue that the presence of rudiments in different animals, in different comparative states of development or efficiency, or in a purely useless condition, can only be explained by a descent from some remote common progenitor, is what the logicians call a _non sequitur_. It overlooks the illimitable faculty of the creating Power, and disregards the great fact that such a power acts by an economy that is saving where uniformity will accomplish what is intended, that is profuse where variation is needful, and that can guide its own exertions of power, or its abstention from such exertions, by unerring wisdom, to the most varied and exact results. I trust that by the use of the term "economy" in speaking of what is observable in the works of the Creator, I shall be understood as comprehending both the avoidance of unnecessary and the exertion of all necessary power. Of the degree of necessity in any exercise of a power which we suppose to be infinite, we can only judge by what we can see. If omnipotence and omniscience are to be predicated of the being who is supposed to preside over the universe, it is rational to conclude, from all that we can discover, that, in applying a uniform system of construction to different animals of a certain general class, he acted upon a principle that his unerring faculties enabled him to see was a comprehensive one; and that in producing variations of that system of construction that would result in adapting its uniformity to the varying conditions of the different species, he acted by the same boundless wisdom and power. If these postulates of the Divine attributes are conceded, rudiments do not by any means necessarily lead to the conclusion that all the animals of a certain class are co-descendants from some remote common progenitor, for they do not exclude the hypothesis that each distinct animal was formed upon a general plan of construction that could be applied throughout the class, but that it was varied according to the special conditions of its intended being. Organs or parts may thus have become more or less rudimentary without resorting to the supposition of a common progenitor for the whole class. That supposition, indeed, makes it necessary to assume that the infinite Creator fashioned some one animal, and