Consciousness (not to be confused with the mind) is the most fundamental manifestation of reality. It is everywhere since matter is sentient. Consciousness is the container of matter and not the other way around. While material world is a fundamental manifestation of the absolute reality, consciousness is more fundamental.
Consciousness cannot be denied
One must only have to think about Descarte's Cogito Ergo Sum to acknowledge that oneself's consciousness is the only certain thing to exist. One could argue that we could be deceived into believing consciousness to be true while it isn't, but to be victim of such a deception, we need to have a consciousness. On the other hand, everything we perceive through our senses could be false in a way similar to the movie The Matrix.
Everything we perceive is consciousness
We see reality through our senses as qualias. When we look at the world, we only see a representation of the world as consciousness. We never see the world in itself through our senses (which includes the thinking mind). To see the world as it is, we must use consciousness itself to look at consciousness itself.
There is consciousness everywhere
When we dream
We assume that other human beings experience consciousness because we belong to the same species. Other animals also experience consciousness even if somes are not aware of conceptual representation. They can still experience the state of affair as it is with immediate perception free (or not) from categorization of conceptual representation. As long as something is perceived (sensory input, emotions etc), consciousness is present.
Plants, stones, cells, particles
Consciousness is structure sentience. Even plants, bacterias and atoms are experimenting beings. The chemical activity of a human brain's neuron is not different from any other kind of chemical activity. Sentience is consciousness's substance while its structure is conceptual. When comparing humans to plants, only the conceptual structure's complexity changes. When sentience is poorly structured, qualias behave like white noise because they are out of phase between each others. On the other hands, when sentience is structured enough, some qualias are amplified since they are are in phase while some others are attenuated.
Matter can only exist inside consciousness
Because consciousness exists everywhere, matter is never separated from consciousness.
Only consciousness truly exist
Modern physics has demonstrated that the closer we look at microscopic particles, the more we realize they contain empty space between their component. Space seems to be pretty much empty. As quantum physics demonstrated, empty space is extremely abundant in energy, the component of matter. The only difference between matter and empty space is the structure of energy, and that structure is of a purely conceptual nature. Matter can be said to be "structured empty space". I recommend you to look at the 'The primacy of Consciousness' presentation from Peter Russel.