This is the first sloka of one of the great works of KaaLidhaasa, Raghuvamsa Mahaakaavya. This sloka indicates the unity of Lord Shiva and Shakthi. Lord Shiva is the immortal paramaathman which is always enjoying in the self. When It intends to create the worlds the Shakthi emerges out . When all the worlds that are created are active the Shiva and Shakthi appear to be two different entities, but they are the same Truth. When everything finally become inactive into the Lord during the Mahaa Samhaara time (Destruction) Shiva and Shakthi will become one and the same. There is a nice hymn in the starting of Kaliththokai (A Tamil sangam literature - B.C.) which praises the Dance of destruction that the Lord do, in which he describes the stillness of Shakthi in the Mahaa Samhaara time.
In this hymn KaaLidhaasa describes the inseparability of Shiva and Shakthi with two nice examples. Every word in any language has its sound also. When we look into the word we automatically remember the way it is read. They are always together. Similarly every word has its own meaning. It is not possible to say the word alone and not convey its meaning or without the words trying to say something. When we think of the word automatically its meaning comes into our mind.
They are inseparable like the word and its sound (the way it is read), and like the word and its meaning. To those Parvathi and Parameeshwara, who are the parents of this world, Salutations.