Stop reading when you no longer agree.
Sun beating, rain falling, grass growing.
Sun does not cause the grass, the grass does not invoke the sun.
An interplay, seemingly on automatic.
Science can identify features of the grass where sunlight, rain and earth are combined. The very reasons for the grass, rain, earth or sun are not to be known. Evolution can inform us that grass was the best fit for the role and the apparent design fits the job done so well as all other attempts fell by the way side.
Your heart beats. Your breath is often unguided by you, as you sleep, in much of your wake, the lungs rise and fall. In a way, very unlike the grass, you feel that you are someone, you can pause your respiration and set it off again. Not indefinitely, but there is a feeling of control, not over your heart beat, your mind forming images from light and surface, not over when and which thoughts arise or dissipate, not on how much your fingernails will grow in a second, not over your height age 3, but you feel control over some things. That is what you are, you may think.
Lets say that the top of the spine and the bulk of the brain take care of that which makes for an animal and that there are areas where additional processing may take place, for example the frontal area in the brain, which, by evolution, have set us apart from animals and provided a higher individuality and feeling of self. Is that self then real? Or a set of survival tendencies charged with key roles such as spreading and processing information and ideas within generations rather than, as standard evolution goes, over many generations?
Both answers are complementary and need not actually be chosen between, yet hundreds more exist, hundreds of ways of explaining what we are, why we act the way we do feel the way we do, why we're here, where we're going and whether that is right, wrong or the only possible outcome. As with the grass and the sun, the answer is unknown but in a grander way, the answer is unknowable. The very knowing, one way or another, is only an opinion of the very subject matter at hand, so may well be a complex justification for what is already the case or a pitifully weak explanation.
The answers are not in the mind.
Take an area of space, 3 feet ahead, 3 inches up and a foot to the right. Just over there in front of you. In the air. Zoom in to that space and the invisible gasses move in currents that great mathematicians and powerful computers can't strictly model or predict. Zoom into the atoms that you or science can't truly depict. Zoom into the level where quantum physics say that "It is not stranger than we suppose, but more strange than we can suppose" and along side the supposed particles, that aren't really particles, is a lot of space, full of forces, that you can't explain. The particles that aren't particles are not made of bits and are primarily empty, and so on and so on. We reach a place where there is 'not a something'.
Zoom into any area in the room, deep in a cushion, inside the liquid in your drink, inside your body, and zoom and zoom, you'll find 'not a something'. Go into the depths of space and while we're at it, to save time, go into the depths of star, zoom and zoom, you'll reach 'not a something' in both places and anywhere else you look.
The mind needs things, names for things and explanations of relationships between those things. Yet everywhere you go, as soon as you delve deep enough 'not a something' is there and the mind must draw closure on desire for explanation.
As the space just over there and deep space, and the core of a star, core of an apple, each neuron in your brain, each hair, each flake of skin, cell, anything, anywhere, is ultimately 'not composed' of 'not a something' then there is no you, no star, no space, and .... all is a oneness.
In the mind, in part the automated section and in part the 'free thinking me' section, parts are formed, named, given interactions, given reason, given cause and so the world, made of mind. The world is a construct of the mind and in reality, not a thing exists.
The 'not a something' is THAT and when we say; That is a tree, that is a brick, that is a hair, that is a person, we are saying that 'not a something' is appearing, via the mind, as X.
The power of the meditation Neti Neti (not this, not this) is to see that THAT is all there is, THAT is what you are, not this person, but the same that that is the air over there, the same that that is everything, you are that. In hearing writings that come from the Neti Neti school "You are not happiness, you are not sadness you are not the perceiver you are not the perceived, you are not life you are not death...etc etc" then remember to add: "You are not happiness, because you are that (the one mentioned above), you are not sadness, because you are that, you are not the perceiver, because you are that, you are not the perceived, because you are that, you are not life, because you are that, you are not death, because you are that...etc etc"
You can check out Ta-Wan's other musings here.