"In these unequal unions, when the male exceeds the female in point of size, his union with a woman who is immediately next to him in size is called high union, and is of two kinds; while his union with the woman most remote from his size is called the highest union, and is of one kind only. On the other hand, when the female exceeds the male in point of size, her union with a man immediately next to her in size is called low union, and is of two kinds; while her union with a man most remote from her in size is called the lowest union, and is of one kind only. In other words, the horse and mare, the bull and deer, form the high union, while the horse and deer form the highest union. On the female side, the elephant and bull, the mare and hare, form low unions, while the elephant has and the hare make the lowest unions. There are, then, nine kinds of union according to dimensions. Amongst all these, equal unions are the best, those of a superlative degree, i.e. the highest and the lowest, are the worst, and the rest are middling, and with them the high 1 are better than the low. There are also nine kinds of union according to the force of passion or carnal desire"
Gosh they spent A LOT of time thinking this through, didn't they?