There's this thing. It's important. It is variously referred to as attention, awareness, Mind (capital M) and sati.
I like to call it Light (capital L). It fits.
We're all pretty familiar with Light.
It's like a finger. We touch things with it, and direct it at things. We direct our Light at sights, sounds, thoughts, feelings, dogs, cats, people and stuff we're doing.
When we direct our Light at a thing we see the thing more clearly. Details become evident.
When we withdraw our Light from a thing we see it dimly. We cease to take note of it or its details. Our view of it fades.
When we get distracted by a thing our Light gets drawn to that thing against our will. A loud sound or an itch. We have something we'd rather attend to, but the itch keeps pulling us away.
When we focus on a thing, when we give the thing our prolonged and intense attention, then we see it very clearly. Depths and richness reveal themselves. It may become beautiful to us.
When we ignore a thing completely it fades from our perspective entirely. It becomes invisible to us.
We give our Light to important things and ignore unimportant things. That which we give our Light to offers up a wealth of important details. That which we ignore does not. So you see how these things can spiral.
Light plays a key role in the construction of our reality. Determining what's visible and invisible, the important and the unimportant, the beautiful and the ugly.
The Buddhists and Zennists call attention "Mind" (Capital M) or "awareness".
(This can be a little confusing because in our society we use the term mind to refer to our intellect. Our pile of ideas, memories, mental space where we think about stuff. Supposedly somebody translated awareness as mind once upon a time, so now we're stuck with it.)
Light is formless. Like a cloud or a blob of water. It can take any shape, move all kinds of ways.
It's what we manipulate in meditation.