Adi Shankara 
Seer and Seen
1.The form is seen, the eye is seer; the mind is both seen and seer. The changing moods of mind are seen, but the witnessing Self, the seer, is never seen. 
 
2.The eye, remaining one, beholds varying forms; as, blue and yellow, coarse and fine, short and long; and differences such as these. 
 
3.The mind, remaining one, forms definite intentions, even while the character of the eye varies, as in blindness, dullness, or keen-sightedness; and this holds also of hearing and touch. 
 
4.The conscious Self, remaining one, shines on all the moods of mind: on desire, determination, doubt, faith, unfaith, firmness and the lack of it, shame, insight, fear, and such as these. 
 
5.This conscious Self rises not, nor has its setting, nor does it come to wax or wane; unhelped, it shines itself, and illumines others also.