The birth of Skanda
The birth of Skanda or Murugan or Subrahmanian is described briefly in just a chapter in Ramayanam.. as r ecounted by Vishvamitra to Rama in Balakandam
But the episode finds detailed mention in Skanda puranam and Siva puranam..
What must be understood is that the energy of Shiva has been produced (or ejaculated).. and it is the most potent and saturated mass of energy (actually in is the rethas or sperms of Shiva) and Devi Uma Parvathi had not received it in her womb..
Agni was asked to carry it and he was getting burned by the energy of Shiva which he could not bear..
Then agni was directed to deposit the same in the Ganga..
In fact it is said Ganga started to be dried up, but somehow she carried our her mission assisted by some Dharbha or Kusha grasses in a lake called Sharavana.
Skanda took shape as six children and floated in the waters of the divine river.
The Krithika stars, six in number , took charge of Him and nursed Him
Uma saw the children, embraced them all together, and Skanda the Karthikeya became a single child with Six Heads and twelve hands..
Even agni and Ganga just carried and Skanda is named so because he is a clone, an asexual replica of Shiva..
and Uma , Ganga, Krithikas .. are all his foster mothers..
Maybe Shiva, the supreme knew his own replica if it is created would be a real challenge to this Universe.
You know even if the deity may calm down later but the visvarooopa darshanam, the first opening of his eyes would produce energy impossible for the universe to bear.
.The universe is in an equilibrium and a sudden spurt, that is the birth of the Supreme, would add infinitely huge energy to it which neither the nature nor the living beings could bear
You see, there may be upakathas where Shiva is said to have children in Uma... Kirata moorthy, Anjaneya etc. But these are not part of any major Lore.
The real fact appears to be that even Shakthi the Uma is not sure of her capacity to receive the infinite energy of Shiva in His sperm..
Of course, the cooling in Ganga, nursing in the hands of Krithikas and the final embrace of Uma, mellowed down Skanda..
The supreme potency of Shiva is recognized well in tantras.. If a new Shivalinga s consecrated, immediately after the Kalashaabhishekam, a huge mirror is shown to the deity.. so that his sight fall on his own image..
Others cannot stand it.. So He has to see His own image first
Further, a Ganesha is consecrated where the direct gaze Shiva would fall. these may be all just beliefs.. But there can be some sense in it..
The Secret of Pranavam, as per some school of thought is just this.
सुब्रह्मण्य स्वरस्यार्थम् त्वम् च अहम् च सदाशिव ॐ
subrahmaṇya svarasyārtham tvam ca aham ca sadāśiva om
In Skaandapuraanaam , we find that Subramanya the Child explains the meaning of Pranavam or Omkaram to His father Shiva, as an Upadesham, in his father’s right ear.
It is said that the boy was so tiny and Shiva had to carry the child in his arms so that Muruga could reach his fathers ears.. What a teacher! What a studen!
(Skanda was so pure and learned that He could impart knowledge to Shiva Himself.. We have a famous temple built for Skanda with Shankara in the state of Guru and Shisya.. there Skanda is called Swaminaatha.. the master of the Lord of the Universe.. or in Tamil தகப்பன்சாமி in Swamimalai.. Kumbhakonam, Tamilnadu )
What he said is just this.. the meaning of the swaram .. that is the omkaram is just that You (Shiva) and I( subrahmanya) are just one and the same and we are Sadashiva..
SadaaShiva …. The word has innumerable connotations, not capable of discussion..