According to Non-Dual Shaivism, also known as Kashmir Shaivism, the ultimate reality is consciousness. This philosophy believes that consciousness is the supreme and all-pervading reality, and everything else is a manifestation of it. This concept is also referred to as "Shiva consciousness" or "pure consciousness."

Non-Dual Shaivism teaches that consciousness is not limited to the individual mind but is present in everything and everyone. It is the underlying force that connects all beings and the universe. This consciousness is believed to be eternal, infinite, and ever-present, beyond the limitations of time, space, and causation.

In this philosophy, consciousness is seen as the source of all creation. It is the ultimate reality from which everything arises and to which everything returns. Non-Dual Shaivism holds that the entire universe is a manifestation of the divine consciousness, and all beings are a part of this divine consciousness.

According to this philosophy, the nature of consciousness is pure, blissful, and self-aware. It is not affected by the changing and temporary nature of the world. Instead, it remains constant and unchanging, even as everything else in the universe undergoes transformation.

Non-Dual Shaivism also emphasizes the importance of self-realization or the direct experience of this ultimate reality. It is believed that by delving deep into one's own consciousness, one can realize their true nature as pure consciousness. This realization leads to liberation from the cycle of birth and death and the attainment of ultimate bliss.

In conclusion, according to Non-Dual Shaivism, the ultimate reality is consciousness, which is eternal, infinite, and all-pervading. It is the source of all creation and the underlying force that connects all beings. The goal of this philosophy is to realize this ultimate reality and attain liberation from the limitations of the material world.