Advaita means nondual or not two. This oneness is a fundamental quality of everything. Everything is a part of and made of one substance. Often the question arises, If it is all one thing why dont I experience it that way? This is confusing oneness for the appearance of sameness. Things can appear different without being separate. Just look at your hand for a moment. Your fingers are all different from each other, but are they separate? They all arise from the same hand.
Similarly, the objects, animals, plants and people in the world are all definitely different in their appearance and functioning. But in their ultimate nature, they are all connected at their source. So, this one Being has an infinite number of different expressions that we experience as different objects.
Isn't it true that your fingers are all made of the same stuff? As you explore more deeply the nature of your own hand, you may discover more ways the fingers are actually the same. They consist of similar tissues, cells, and ultimately atoms. As your experience of becomes more subtle, you find everything is a different expression of one Being.
What about right now? Can you find this subtle oneness in your present experience? You can, if you let go of any expectation of a profound experience of oneness and instead explore a little bit of oneness at a time. Every single drop of water is wet, and so you can experience Advaita or oneness in every little part of existence. This oneness is fundamental to everything that exists.
Let's try something: look closely at your fingers and then at the palm of your hand. Where do the fingers start and the palm of your hand end? Or are they really one thing? Going even further, where exactly does your hand end and your forearm begin? Can you experience how your hand and forearm are really one thing?
Let's also check all your bodyparts? Are your legs and your nose really connected even though they sure look different? And even more subtlely, how separate are your thoughts and your mind or brain. Exactly where does the head stop and thinking begin? And how about sadness and fear and desire? Are feelings and wants really things that exist separate from you?
Now, notice the simple sensations you are having: the sounds you are hearing, the sensations of touch, and the objects and events you are seeing. If you are seeing something, where does the seeing stop and something else called the eye begin? If you are hearing sounds where does the sound start and the ear stop? Perhaps the hearing and the sound and your ear are all one thing. Yes, the ear is different from the sound, but in the act of hearing they become one thing.
Then the question arises, what about the source of the sound? For instance, if a dog is barking outside, where does the dog stop and the sound of barking begin? Or are they really one thing? If a dog and its barking are one thing, and your ear and the sound are also one thing, then you and the dog must be one thing also.
Oneness of Being, or Advaita as it is called, has been believed to be something quite rare and hard to experience. But it is actually quite ordinary and available in everyday experiences. And overwhelming experience of the totality of oneness may be a rare and extraordinary event. But why not taste this sweet, satisfying oneness right here, right now in this ordinary moment?