A merchant crossing a forest infested with thieves would keep a weapon ready to hand. A traveler passing through a country ravaged by plague would take with him an assortment of medicines. In the same way, living as you do under the constant threat of emotions like anger, desire, pride, jealousy and many others, you should always be ready to fight them off with the appropriate antidotes. Constant vigilance is the mark of a sincere practitioner. You may know how to practice when everything is going well, but that is of little use if you succumb to the first emotion that hits you.
Good practitioners can be recognized by their response to difficult situations liable to provoke latent emotions. Those capable of reacting immediately with the correct antidote will have no problem overcoming obstacles.
In particular, if they know how to transcend the concepts of subject and object, all their thoughts will liberate themselves, like a snake wriggling out of the knots tied in its own body, without effort or help. When you trace all thoughts and concepts back to their very source, you will recognize that they all have the same true nature – emptiness inseparable from transcendent wisdom.
~ Dilgo Khyentse Rinpoche