Many people ask, what does the word "Tatlum"? OK! Answer: An ancient poem has handed down the secret of this magic stone. It is there called a tathlum, meaning a "concrete ball" such as the ancient Irish warriors used sometimes to make out of the brains of dead enemies hardened with lime.
"A tathlum, heavy, fiery, firm,
Which the Tuatha Dé Danann had with them,
It was that broke the fierce Balor's eye,
Of old, in the battle of the great armies.
"The blood of toads and furious bears,
And the blood of the noble lion,
The blood of vipers and of Osmuinn's trunks;--
It was of these the tathlum was composed.
"The sand of the swift Armorian sea,
And the sand of the teeming Red Sea;--
All these, being first purified, were used
In the composition of the tathlum.
"Briun, the son of Bethar, no mean warrior,
Who on the ocean's eastern border reigned;--
It was he that fused, and smoothly formed,
It was he that fashioned the tathlum.
"To the hero Lugh was given
This concrete ball,--no soft missile;--
In Mag Tuireadh of shrieking wails,
From his hand he threw the tathlum."
This blinding of the terrible Balor turned the fortunes of the fight; for the Fomors wavered, and the Morrígú came and encouraged the people of the goddess Danu with a song, beginning "Kings arise to the battle", so that they took fresh heart, and drove the Fomors headlong back to their country underneath the sea.