Recently, a post on Facebook asked, "Do you need a teacher in a physical body if you want to attain self-realization?" This is a good and important question.
First, we'll consider the basic question of whether you need a teacher at all.
A carpenter learns the trade from a master carpenter. Sure, one could learn on his/her own, make all the mistakes and find ways around them, and attain some level of competency. However, the learning would likely be much faster, and better practices would be learned, from a master carpenter.
So how is yoga different? The brief answer is that it's not different. We may think we can pick up a book on yoga learn what we need from it. But, yoga, isn't like that. Even if all we want from yoga is a physical workout or some health benefits, we still need a teacher. This is because each person's personality and habits are different and so each person needs different practices. A qualified teacher can advise which practices to do.
The need for a competent teacher is far greater when one is seeking the ultimate goal of yoga, union with the True Self.
First, we need a guide. Not having a competent guide is like beginning in San Francisco and hoping to drive to New York City without a map. You could possibly do it, but it will likely take much longer than if you have a guide. The landscape of consciousness is far more vast than the USA; there are levels of consciousness, incredible pleasures, worlds within worlds, so many places where one could become stuck or lost.
For such a journey, the help of one who has made the journey before, who knows the lay of the land, the shortest routes, where the dangers lurk and how to avoid them, is essential.
Second, we need a guide who is other than our ego. To attain the goal of yoga, liberation or self realization, we need to release our identification with all the things we identify with, such as our personality, body, emotions, and contents of the mind, and shift that identification to pure being. This means overcoming the process within our mind, called ahamkara in Sanskrit and often called ego in English, that identifies with things. But, if we have no external teacher, then our ego will have to overcome itself to reach our goal, and you can imagine how that will go. From inside the box of the ego, we don't have the perspective needed to throw off the ego. Only someone who has overcome his or her own ego will have the clarity to help us in this task.
Let me give an example. Many years ago, my parents visited me when I was living in the San Francisco area and my dad and I had a nasty argument. I felt bad with what happened and consulted my meditation teacher, Swami Veda Bharati, asking him what to do. His answer was to "revere your parents." Honestly, I had no idea how to do that. So over the following weeks, months and years, I made it my practice to learn how to revere my parents and to do so to the best of my ability. Over time, Dad's and my relationship completely changed to one of love and appreciation from its previous dysfunction. Actually, my relationship with both my parents transformed in this way.
Righting my relationship with my parents freed up energy that I could then use to deepen my spiritual pursuits. Without the outside perspective of Swami Veda, I would not have known how to do this.
So, in summary, a teacher is a necessity to learning the practices and processes one needs on the path of yoga. Both as a guide, so one can stay on the path, and for overcoming the ego.