Thomas Aquinas

“ In other animals, and in plants, mention is made of genus and species, to denote the generation of like from like. But it was unnecessary to do so in the case of man, as what had already been said of other creatures might be understood of him. Again, animals and plants may be said to be produced according to their kinds, to signify their remoteness from the Divine image and likeness, whereas man is said to be made "to the image and likeness of God." ”

“ The blessing of God gives power to multiply by generation, and, having been mentioned in the preceding account of the making of birds and fishes, could be understood of the beasts of the earth, without requiring to be repeated. ”

“ Since the generation of one thing is the corruption of another, it was not incompatible with the first formation of things, that from the corruption of the less perfect the more perfect should be generated. Hence animals generated from the corruption of inanimate things, or of plants, may have been generated then. But those generated from corruption of animals could not have been produced then otherwise than potentially. ”

“ Further, certain animals are poisonous, and injurious to man. But there ought to have been nothing injurious to man before man sinned. Therefore such animals ought not to have been made by God at all, since He is the Author of good ”

“ And thus some people presume to find fault with many things in this world, through not seeing the reasons for their existence. For though not required for the furnishing of our house, these things are necessary for the perfection of the universe." And, since man before he sinned would have used the things of this world conformably to the order designed, poisonous animals would not have injured him. ”