If you see some pictures of Lord Shiva ,there is a third eye on his forehead which is mostly half closed. This third eye is highly symbolic.
According to Hindu mythology, Lord Shiva is the God of destruction, he is also the Beginning of Creation. In fact, his ‘Tandav’ dance symbolises cosmic dance of the universe, which is the cycle of creation , preservation and Destruction.
Whenever corruption and sins go out of proportion in the universe, Lord Shiva opens his third eye to destroy them and bring balance or order in this world. There are various interpretations about it.
One such theory is that , since Lord Shiva is Yogi his third eye symbolises inner eye or spiritual eye which see the world beyond the material world.
When our two eyes become blind or get lost in the gloom and corruption of the material world then we have to try to see through our inner eye which is obviously difficult.
While our two physical eyes see the world and get lost in the illusion of past and future, our inner eye exist in the eternal ‘Now’ and helps us to know the real meaning of our existence.
This inner vision is a practice, a kind of meditation which enables us to live in the present which is devoid of any negativity of past and future. It calms us , give us peace and help us to see the physical world with a broader perspective.
Today is Mahashivratri, the great night of the lord Shiva. It is the night of unison of Shiva and Shakti (union of Universe’s Dark Matter and energy)– the embodiment of love, power, and oneness. May this occasion opens the inner eye of this already troubled world and brings happiness and peace in this world.
Lord Shiva and his Dark energy and matter , you can read this article here https://theperceptionssquare.com/2020/02/21/lord-shiva-and-his-dark-energy-and-matter/