The eyes and the other senses are for only receiving impressions of form, etc. The mind exists for doubting. The Understanding determines those doubts. The Soul is said to only see every work without mingling with them.
चक्षुरालोचनायैव संशयं कुरुते मनः। बुद्धिरध्यवसानाय साक्षी क्षेत्रज्ञ उच्यते॥