Kamasutra 7.2.55

7.2.55

na śāstram astīty etena prayogo hi samīkṣyate/
śāstrārthān vyāpino vidyāt prayogāṃs tv ekadeśikān//

An act is never looked upon with indulgence for the simple reason that it is authorized by the science, because it ought to be remembered that it is the intention of the science that the rules which it contains should only be acted upon in particular cases. After reading and considering the works of Babhravya and other ancient authors, and thinking over the meaning of the rules given by them, the Kama Sutra was composed, according to the precepts of Holy Writ, for the benefit of the world, by Vatsyayana, while leading the life of a religious student, and wholly engaged in the contemplation of the Deity.