It is true. Communication is the key to any successful relationship. Especially when it comes to something like Kamasutra. It is the duty of each partner to ensure that they are satisfying their lover, but it is also their duty to let their lover know how they are feeling.
Humans are not mind readers, and often times do not know what you are thinking. You have to be open with your partner and allow your partner to be open with you. Otherwise, you will have some serious issues. A lot of times people are not open because their partners shut them down, and get angry at criticism, so they feel that they are not able to be open. You have to encourage communication both in and out of the bedroom.
In the bedroom, make your partner feel comfortable with vocalization. If they are nervous, let them know that it is not silly, and you like knowing that what you are doing feels good, or if it doesn't feel good, you want to know so that you can make the proper adjustments. You should also lead by example.
This book covers:
And much more!!!