The opening verse of Drig Drisha Viveka states:

Form is the seen, the eye is the seer; 

that eye is the seen, and mind is its seer;  

thoughts in the mind are seen by the Witness

which alone is the Seer, but can never be the seen.

—Drig Drisha Viveka, trans. and commentary by Swami Gurubhaktananda

Swami Gurubhaktananda nicely points out that in this verse we find “all four levels of existence.” 1. Form refers to “all the physical sense objects of this universe.” 2. The eye “stands for all the five sense organs of perception.” 3. The mind “includes the entire inner equipment called
Antahkarana (mind, intellect, memory and Ego).” 4. And the Witness refers to the “supreme Self.”

Thanks to the direct path teaching of Atmananda, we might simplify what’s said in the following manner. Since seeing never appears apart from form, seeing and form are identical. They are, in fact, already “subtle” in the sense that seeing-form is appearing within space, a concept. The stuff of seeing, in other words, is already subtle.

The mind, which is only thought or a thought-form, can never actually be a seer because it is inert. Moreover, there’s no such thing as thoughts occurring “in the mind” because thinking is nothing other than mind, mind nothing other than thinking.

In which case, we’ve collapsed or compressed the first three lines into one: the subtle is appearing to the witness. And the witness, indeed, is beyond the subtle. Finally, it’s verifiable that the witness can never be the seen.

In other words and put as simply as possible: a subtle object is appearing to the witness, and the witness can never be an object.

The crux, in this understanding of the viveka approach, is that you are always the witness and the object is always appearing to you.