With the five senses of knowledge and five senses of action, the mind makes a total of eleven. The twelfth is the Understanding. When doubt originates about what is to be known, the Understanding comes forward and sets at rest all doubts,
द्वादशस्त्वपरस्तत्र बुद्धिर्नाम गुणः स्मृतः। येन संशयपूर्वेषु बोद्धव्येषु व्यवस्यति॥