In plain words
We are safe when those who hate us and those who mean to seize our kingdom do not enter our country. Since, on the contrary, they were trying to enter our country, these safeguards were set up with the one intention of catching such thieves. Night and day they kept a careful watch. Meanwhile someone came as a thief to get in. Then a soldier caught him. The master was in his tent. This soldier gave a loud shout: “Sir! Sir! I have caught a thief,” he said. The captain told him to bring him into the tent. The soldier: ‘Sir! He says he won't come there,’ he said. ‘Then at least you come here,’ he said. ‘He won't let me go either,’ the soldier said. Its inner meaning is this: the soldier was posted there to catch thieves, and he fell into the thieves' hands. How can he catch these thieves any more? In the same way, students who came to pursue learning in order to control the senses are today falling under the power of the senses. A certain weakness has come into the soldiers. You must be great soldiers. You must keep within bounds the bad qualities that torment you. Those who cannot keep them under control in this way can never be students. The senses are man's worst enemies. They go only the way they please. So what is the easy way to control them? The spiritual alone is the easy way for this. When there is true devotion to God and faith in our heart, the senses cannot torment us at all. It is only because such Bhakti and surrender have grown somewhat weak in us that we are falling under the power of the senses. So, whatever activities students are in, they must first enquire whether the work the senses do is good or bad, and try to conduct themselves to the true satisfaction of their conscience.
Here there are some faults in conscience too. One conscience works only with cleverness; the second conscience thinks with the heart.