Many facets of truth
We know two states, the extrovert mind and the mind in deep sleep, the extrovert mind is conscious.
Every God and Goddess in Hinduism can be understood from four standpoints: the absolute, the cosmic, the "departmental," and the incarnation who appears on earth to re-establish dharma.
From the highest standpoint, Lord Shiva is the formless absolute Reality, which is of the nature of pure consciousness. Shiva's name itself means auspiciousness. There is a similar sounding word in Sanskrit, shava, which means a dead body.
A body is nothing but inert matter — a corpse; until Shiva's presence transforms it into a beautiful thing. That divine presence is the pure consciousness, Shiva, and it is one's own true nature.
From the cosmic viewpoint, Lord Shiva represents the Lord of the universe — the creator, sustainer and destroyer of the world.
From the departmental standpoint, He is worshiped as the deity in charge of the power of destruction. Thus, we invoke the name of Lord to give us the capacity to destroy our attachments and ignoble thoughts.
In His fourth aspect as a particular form that manifested on earth, Lord Shiva is said to have appeared in numerous incarnations as a guru avatar, an enlightened master who teaches the knowledge of the self to his disciples. Sri Adi Shankaracharya and Dakshinamurti Bhagwan are considered to be such avatars of Lord Shiva.
In his Ramayana, Goswami Tulsidas explains that Lord Shiva is Brahman and Parvati is Adi Shakti, the Lord's primordial power. Tulisdas also points out that the Lord embodies faith that is essential to realisation of truth. Yet, even if we have faith, we are unable to see the truth unless we have a teacher to guide us. Thus, Lord Shiva is the supreme Brahman, the faith by which we realise the truth, and also the guru who guides us.
On Shivaratri, devotees continuously chant the name of the Lord and concentrate until midnight when it is said that Lord Shiva manifests Himself as the light of consciousness within.
At present, we know only two states — the extrovert mind and the mind in deep sleep. The extrovert mind is conscious of and indulges in the world outside through the five sense organs. The mind in deep sleep is in a state of total ignorance, completely unaware of the world. That is why, one is supposed to stay awake all night during Shivaratri In this state of objectless awareness comes the moment of spiritual awakening — the true Shivaratri!