Mudra is a Sanskrit word denoting connection and direction of subtle energies. This discussion is not a detailed presentation of one of the main divisions of Hatha Yoga called Mudras. Just using this idea to talk about how important connections are in yoga.
Sometimes yoga can be viewed as a pre-eminent method for coming into ones true nature. Now the popular view of yoga is mainly from asanas. How many times have you heard how hard or wonderful yoga class was on a particular day. Meaning that we are only emphasizing the physical part of using asanas (sadly just for exercise).
The richness of yoga is developed through these subtle connections. Starting with our own energy systems and pranic flows and moving into connections through initiation.
When one develops a deep relationship there is an actually felt connection. Take when you in love with someone. You can feel without words or actions how the other person is doing. Sometimes there is a tandem of thoughts and small movements that are not rehearsed or overtly noted. There is just this strong connection on the inside that is shared both from within and without.
This is how a mantra works that is given in initiation of a tradition. This connection of the mantra is internal and subtle. This relationship is to that which is eternal and true. This is love. Without this connection it becomes very difficult to find your way in this journey of the revealing Self.
Having a guide is immensely helpful. In this case a mantra given by a master acts exactly like a guide. It helps in this subtle differentiation between what is real and what is not. This knowing only comes about through practice and grace of this connection. For some this connection is a deep knowing and experience which continues to shine within like a beacon. There is always something of great and often subtle importance that takes place within ones experience that leads one inwards.
Trying to do yoga from the mind or body is incomplete. The ego of ourselves often confuses the direction of what is truth. So many things get in the way that we easily can be come distracted. It is important to consider giving up ones egoistic self. To consider coming with open hands and heart into this deeper connection within. This connection is made through initiation.
Initiation is only being introduced here. It is a much larger topic. Many people have an aversion to the concept of it as it appears to resemble a cult like behavior for some. Here initiation is compared to finding a lover that takes us to sublime places and spaces that we otherwise would miss and avoid. This lover is love itself. The path is not always pleasant. The richness of yoga through this connection of love . Great effort, focus and practice is the work of preparation for this journey.