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.
It is just the little difference between the good and the best that makes the difference between the artist and the artisan. It is just the little touches after the average man would quit that makes the master's fame.