Secondly, man sins against nature when he goes against his generic nature, that is to say, his animal nature. Now, it is evident that, in accord with natural order, the union of the sexes among animals is ordered towards conception. From this it follows that every sexual intercourse that cannot lead to conception is opposed to man's animal nature.
Thomas AquinasHow is it they live in such harmony the billions of stars - when most men can barely go a minute without declaring war in their minds about someone they know.
Thomas AquinasFor it is necessary in every practical science to proceed in a composite (i.e. deductive) manner. On the contrary in speculative science, it is necessary to proceed in an analytical manner by breaking down the complex into elementary principles.
Thomas Aquinas