As the tortoise extends its limbs and withdraws them once again within itself, so the Understanding creates the senses and once again withdraws them into itself. The consciousness of ego which arises about what is above the soles of the feet and below the crown of the head, is mainly due to the action of the Understanding.
यथा कूर्म इहाङ्गानि प्रसार्य विनियच्छति। एवमेवेन्द्रियग्रामं बुद्धिः सृष्ट्वा नियच्छति॥ एतस्मिन्नेव कृत्ये तु वर्तते बुद्धिरुत्तमा॥