Kamasutra 2.1.3

2.1.3

viparyayeṇa viṣamāṇi ṣaṭ/ viṣameṣv api puruṣādhikyaṃ ced anantarasaṃprayoge dve uccarate/ vyavahitam ekam uccatararatam/ viparyaye punar dve nīcarate/ vyavahitam ekaṃ nīcatararataṃ ca/ teṣu samāni śreṣṭhāni/ taraśabdāṅkite dve kaniṣṭhe/ śeṣāṇi madhyamāni//

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 him in 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 and the hare make the lowest-unions.

There are thus three unions between persons of corresponding dimensions, and there are six unequal unions, when the dimensions do not correspond, or nine in all, as the following table shows:

EQUAL. · UNEQUAL.
Men. · Women. · Men. · Women.
Hare. · Deer. · Hare. · Mare.
Bull. · Mare. · Hare. · Elephant.
Horse. · Elephant. · Bull. · Deer.
Bull. · Elephant.
Horse. · Deer.
Horse. · Mare.

There are then, nine kinds of union according to dimensions. Amongest all these, equal-unions are the best, those of a superlative degree, i.e., the highest and lowest, are the worst, and the rest are middling, and with them the high are better than the low.