attention is a spontaneous happening. It is undirected. Like a cloud in the sky, or a wildflower in a field. You can explain it away of course, and try to enrobe it with words. But the practical experience of attention is that it goes wherever it wants to go. You may feel like you are directing it toward your work, or to reading your computer screen, but the impulse to direct it, is itself spontaneous and undirected.

IOW, you can say the sky manifests the cloud, or the field the flower, but this manifesting is itself spontaneous. It arises out of nothing.

A beautiful image that gives this some texture is one that appears on multiple separate occasions in the Upanishads. I will paraphrase the image here:

Two birds, fast friends, inseparable — sitting on the selfsame tree. The first bird eats from the fruit of the tree of life — here a sweet fruit; there a sour fruit. The second bird watches.

The first bird is the one who judges, who is attention, preference, assessment and evaluation. It is also known as the monkey mind, thinking mind. It is also the mind that uses words and symbols to describe and assess the world. To point to the world rather than look directly at it.

The second bird does not eat the fruit. It only watches. It also does not confer, assess or judge. It does not direct. It has no intention. It only watches. In various traditions, it is also referred to as Brahman, or the Dao, or the Ground of Being. Also, the Kingdom of Heaven / Beatific Vision of God.

Anyway, this two birds image can be used as a powerful aid to meditation and also to trigger awakening, but I will just use it here to answer your question.

The true nature of reality is that only the second bird exists. It is in fact the only thing that exists. It is everything. The first bird is an illusion. It arises spontaneously out of the second bird like a ripple on the surface of the ocean.

The first bird to the second bird is like the cloud to the sky, flower to the field. The sky and field are both the source, and also the impartial witness.

So in the same way, attention arises spontaneously out of the ground of being, along with everything else. Attention is undirected. And also, it is an illusion, like a reflection, because these things do not exist on their own. The only thing that exists is the one thing, the Ground of Being, the impartial witness of all things — and of course, you are the ground, too.