Sadhasiva is the 'first-born son' of Siva

From Siva Parameswara, the 'space' element is manifests first.
Simultaneously, from Siva Parameswara, 'Sadhasiva',
the Lord of the space element, is also born.
Hence, Sadhasiva is the 'first-born son' of Siva Parameswara.

Sadhasiva's Grace-Love is the 'One Way' for merging back to Siva

The 'earth' element merges into the 'water' element,
water into fire, fire into air, air into space and
finally the 'space' element merges back into Siva Parameswara.
The Lord of the 'space' element is Sadhasiva.
Thus, through the boundless Love-Grace of Sadhasiva alone,
one can merge back into Siva Parameswara.

Space is manifested first and demanifested last

'Space' is the first element to be manifested from Siva Parameswara.
'Space' is also the last element to be demanifested back into Siva Parameswara.

Sadhasiva, the Lord of Space showers Grace on All

The Lord of the 'space' element is Sadhasiva.
Sadhasiva removes the veil of spiritual ignorance
by boundless Love on All through His Grace.

Order of demanifestation of elements back into Siva

The 'earth', 'water', 'fire' and 'air' elements are demanifested
respectively into the 'water', 'fire', air' and 'space' elements.
Finally, the 'space' element is demanifested into 'Siva Parameswara'.

Order of manifestation of elements from Siva

From Siva Parameswara, first the 'space' element is manifested.
Then, 'air', 'fire', 'water' and 'earth' elements are manifested in that order.

Who are Prophets and Servants of God ?

A Prophet of God experiences God
during the dream state only.
A Servant of God is experiences God
during both the waking and dream states.