Shiva is not a physical body in reference but is a universal conscious body.
Nagendra haraya Trilochanaya,
My salutations to Lord Shiva whose garland is the king of snakes, who has three eyes, who smears ash all over his body, who is eternal, who is the purest of all and who exists in all the 10 directions of the universe.
Shiva is not a physical body in reference but is a universal conscious body. Consciousness is eternal, all pervasive and the purest aspect of creation. Creation emanates from this pure consciousness (Shiva), sustained and reabsorbed in the same consciousness after a period of time.
This secret is very clearly revealed in the conversation between Shiva and Shakti. The conversation goes like this:
Devi: Oh Mahadev! From where has this universe emanated and where does it get reabsorbed?
Shiva: Devi! Universe is emanated from the unmanifested formless omnipresent pure consciousness (which is also referred as void) and gets reabsorbed into the same consciousness. The unmanifested formless consciousness only manifests into form (universe) and this universe again gets reabsorbed in the same and becomes unmanifested.
In the process of manifestation of the universe, it is the sound that emanates first and that sound is Om. From this Om emanates everything else such as the five elements (ether, air, fire, water and earth), gross worldly objects, senses of knowledge and senses of actions, mind, Vedas, puja, dhyan, etc.
This entire knowledge of manifestation is available in the human body only as this human physical body itself is micro cosmos as against the universe as macro cosmos. Not only the knowledge of manifestation is available in the human body but all the creative powers, shaktis, siddhis, wealth, devi-devatas reside in this body only.
By turning inwardly into this body and by focusing on the mind one can achieve anything in life and attain any state, including my own state of Shiva.
Devi: Oh Mahadev! Kindly reveal to me as to who performs karma and how can one get liberated from karma?
Shiva: Oh Devi: It is the mind which performs karma. All the pious karma and sins are performed by the mind only and it is the mind that suffers and enjoys the fruits of karma. It is the mind that is in bondage and it’s the mind only that gets liberated from karmas.
Devi: Who is he who eats and drinks and who is he who witnesses all the three states of consciousness, i.e. awakened, dream and deep sleep?
Shiva: Devi! It is the prana who needs food. It is the prana who eats and drinks. When one does pranayama and the rate of breaths comes down then the hunger too reduces and when a yogi gets established in samadhi, he doesn’t require any food as during samadhi, the prana is almost still hence doesn’t feel the hunger.
This prana only remains awaken during our awakened, dream and deep sleep state as this prana only passes on the information of these three states to the mind and mind says I slept very well, I dreamt or I enjoyed the bliss of samadhi. When prana leaves the body, the body dies. While leaving the body, the prana takes with it the mind, senses, ego, impressions, karma, etc., to the next body according to the karma of the soul (mind).
Devi: Oh Mahadev! How can ordinary jeeva become Shiva?
Shiva: Devi! In the darkness of ignorance only it is jeeva and in the light of knowledge the same jeeva becomes Shiva. The difference between bondage and liberation is the difference between ignorance and knowledge (knowledge of the self).
When the knowledge of self, the aatma, the pure consciousness dawns on an individual he becomes Shiva. For this knowledge of self one has to go to a guru and surrender himself at his feet and seek knowledge. Upon serving the guru with dedication, by applying his teachings in real life situations and with intense contemplation on the self one attains the state of Shiva very easily and effortlessly. The objective of human birth is to realise the Shiva aspect in him.