Anyone who understands they do not know something or remember something is not stupid, but actually very wise. There is no shame in ignorance. The Vedas were broken in four, and then again, countlessly. "I do not know," "I do not remember" - there is simply too much information for any one person to know, we must explore the limits of our understanding together; even Brahma and Ganesh could not rely on their memories, frenetically writing their notes, and at times collaborating with others who knew more or were more able than even they were! This is living and working together, respecting truth, constantly perfecting and growing; this is friendship. Friendship is the purpose of practice. Eventually, our personal understanding must inevitably improve with time and effort, and we become better. Just as by the persistent efforts of generations our society improves with time as well.
The beginner and the expert face different challenges, and each envies the other. The beginner only notices the expert's skill and experience, thinking that would alleviate their weakness at the unsurmounted obstacle before them; the expert, having broken through that obstacle only to find another of greater magnitude, looks upon the beginner's newness, and remembers when it was easy to learn something new, and the vigor they held before they wearied in exertion. Yet neither the beginner nor the expert has mastered yoga. Yoga is a practice of exertion, of endurance.
The Jnana Yogi envies the physique of the Hatha Yogi, the Hatha Yogi envies the mental power of the Jnana Yogi. Would it not be better for them to love the other's success, and rely on it, like a friend?
This is why success is guaranteed to every Yogi: because they intend to achieve it. And may, despite whatever failings they have, rely on their friends to help them as a vehicle in that success.