How did the master convey the knowledge to everybody without uttering a word? Well, What master actually did was that, he only helped everyone remember the knowledge of self that has been long forgotten. Truth that you are knowledge, and you are yoga. Knowledge that was lost in translation (Bhagavad Gita: chapter 4 verse2). That is the reason, even without saying a word he could convey such a knowledge which everyone understood. Observing a true master and his action is first step of learning, may be that is the reason why this is the first chapter of Yogasutra. What was the significance of the veil? Veil generally signifies Maya of Nature. The Veil which covers the knowledge, like smoke that covers fire. Once the veil/maya was lifted the thousand thoughts (disciplines) of mind were burnt down. When mind had only one thought left (one discipline), knowledge emerged (out of the veil). Showing that path to wisdom is single pointed mind. Please correct if there is mistake in interpretation. Peace to all!