DOWNLOAD (English):
English annotation by Vishnudut1926: This is a Rati-Shastra (Sex-Shastra).
If you cherish Madhurya-Bhava towards Bhagavan Shree Narayana (Sattvika-Madhurya-Bhakti) and especially Shree Krishna-Avatara (that is Rajasika-Tamasika-Madhurya-Bhakti towards Black Kali-Yuga-Avatara of Bhagavan Shree Narayana) it will be quite useful to know.
If you are fond of Rajasika-Bhakti (Shree Radha-Krishna), the knowledge of Rati-Shastra will help you to understand some Rajasika-Bhakti-Rati-Shastras (such as "Shree Govinda-Lilamrita", "Shree Brahma-Vaivarta-Purana" and etc.) better.
See for example, this article explaining nail marks in erotic Krishna Shastras - http://vishnudut1926.blogspot.ru/2017/12/nail-marks-and-rasa-krida.html
Interesting enough, but "Rati-Rahasya" mentions not only G-spot, but some other spots too:
Funny enough, but "Rati-Rahasya" describes Vashikarana-magic, though majority of Tantras/Agamas (especially Sattvika ones!) forbid Vashikarana black magic in Kali-Yuga.
P.S. Only 3 links for download, as the book is not very crucial for my E-Library.
