There is a lovely 16th century kirtan written in Malayalam by the famous poet Thunchaththu Ramanujan Ezhuthachan called Hari Nama Keerthanam, the song of the holy name Hari. Although it sounds like bhakti literature, Hari Nama Keerthanam is full of philosophical understanding and metaphysical truths. It says:
Kanninnu kannu manamagunna kannathinnu,
Kannayirunna porul, thaan ennu murakkum mala,
Vanandamenthu, hari narayanaya nama
Kannu means ‘eye’. It roughly means the eye of my eye is the eye of the mind. Oh, how blissful it is to know that I am the eye of the mind too. Who is the one who sees when I say, ‘I see’? It’s a very interesting question. Let’s look at the process of sight purely from biological point of view. My eyes are open. The instrument of sight—my eye—is made up of different parts of which the very important one is, of course, the lens.
It’s a convex lens and, therefore, any image that I see is reflected into the convex lens. It falls like a camera image on my retina and then, the idea of the image is transferred through my optic nerve to the centre of my brain that deals with vision. So, the optic nerve carries the impressions of what I saw, after which it is processed at the vision centre and sent to the different nerve endings and synapses, which work together in coordination, and then, I know, yes, I am looking at a tree.