Generally speaking God is the product of the imagination of the human
mind. A concept of a complex personality includes - cognition, emotions
and will. And in the realm of Hindu Philosophy also there is a direct
mapping to each of these facets of our personality - God is viewed as
Brahma or the supreme knower, Vishnu - the great lover and Siva - the
perfect will.
Sketch - The Vashisht Temple
Why is "the will” of a personality is attributed to Shiva?
The whole universe at the most elemental level is the limitless number of
interacting subatomic particles and to a Hindu mind Shiva is a
Divine manifestation of this - He is regarded as formless, limitless and
unchanging Brahman, the soul (Atman of the universe).
As a part of its spiritual development the mind carves iconic and an-iconic
representations of its beliefs. And to the Hindu mind the concentration or
condensation of the cosmos is that of the an-iconic Shiva Linga.
The particles of the universe are forever in a pulsating process of
creation and destruction and this is how life functions at the most
elementary level. The energy in this continuous interaction of the
subatomic particles and continuous destruction and creation is
unfathomable. To the mind, which has carved out this image of a lingam to
be a condensation of the entire cosmos, the energy retained in one single
form must also be immense. And this form is eternal and so obviously the
energy or the Tapas is contained within this, circulates within the structure
and does not dissipate. To be able to retain infinite reverberating energy or
Tapas (meaning heat) in one form and that too from eons must be a matter
of great strength and will. This is perhaps why the will of the our
personality is attributed to Lord Shiva and this also explains the depiction
of the Shiva as an ascetic involved in Tapasya. An ascetic retains this
state in extreme conditions only by virtue of great will.
And the dance of Shiva is an energy dance, the dance of subatomic matter, the dance of
creation and destruction involving the cosmos, the bases of all existence
and natural phenomena.