तस्य तत् पूर्वसंरुद्धमात्मन: षष्ठमान्तरम् । स्फुरिष्यति समुदशभ्रान्ता विद्युदम्बुधरे यथा,इस प्रकार प्रयत्न करनेसे जो इन्द्रियोंसहित मन कुछ देरके लिये स्थिर हो जाता है, वही फिर अवसर पाकर जैसे बादलोंमें बिजली चमक उठती है, उसी प्रकार पुनः बारंबार विषयोंकी ओर जानेके लिये चंचल हो उठता है
tasya tat pūrvasaṃruddham ātmanaḥ ṣaṣṭham antaram | sphuriṣyati samudaśabhrāntā vidyud ambudhare yathā ||
Bhishma said: Even when, through prior effort, the mind together with the senses has been restrained and held steady for a time, it flares up again when it finds an opening—just as lightning suddenly flashes within a cloud. In the same way, the mind repeatedly becomes restless and rushes back toward sense-objects, showing how vigilance and continued discipline are required in self-control.
भीष्म उवाच
Temporary restraint is not final victory: even a mind subdued by effort can surge back toward sense-objects when an opportunity arises. Therefore one must practice sustained vigilance (apramāda), repeated restraint, and steady discipline rather than trusting a brief calm.
In Bhishma’s instruction in the Śānti Parva, he explains the practical difficulty of inner governance. Using the image of lightning flashing in a cloud, he describes how the mind—counted as the ‘sixth’ alongside the five senses—can suddenly become active again after having been checked, and thus needs ongoing training.