The primal sources of mana

Everybody knows the great sources of mana in the world, even the children. They grow up under the daily influence of one or more of them - the radiance of the Sun, the waters of the Great Ocean, the shadow of the Arch, the fertility of the Eternal Forest, or the heat of Vezuvus. But this tale does not concern itself with that. The elders of the world know that these wonders only grew out of the leylines that run through our world. Where they come from, now, that is a legend worth telling.

Long ago, when the universe was newborn, there was only the Force, an arcane energy permeating all of existence. It was as it is now, as some of us know it today, everpresent, everywhere, and everywhen. But at the centre of the universe, it pulses, like the beating heart of all that is. As the universe grew, under the guidance of its caretakers, the first objects began to form. The first star was born, and when the beating heart's pulse sent a shockwave through it, the star began to radiate with light. The first quasar grew, and when it was struck by a pulse, it absorbed it and became massive, fluid, and most importantly, aware. The first black hole manifested, and when it felt the heartbeat, it shuddered and hated it, and it began to devour everything it could. The first supernova erupted when the Force pulsed so violently, it destroyed a sun as it was bathing in the light of the first start. The first nebula formed when the Force pulsed gently and lovingly, fusing an enormous cloud of gas with the essence of life.
We know not of what these objects are, we can only dream and imagine of bodies larger than our very own Sun, or even our world. But this is how they were described to me by a living Avatar.

— Arsianna, Supreme Sorceress

Those few who concern themselves with these tales, and choose to believe them, accept also the writings found in the Third Book of Naa'ran:

... and this tells us how the leylines that penetrate all world a thousand times over, came to be:
After the first, many suns soon followed. The eldest ones, together, grouped up and formed a cluster of a thousand suns so big, that shines so brightly, that its emanates pure mana, of the light variety, such that on occasions when this primal leyline crosses with a red one, they merge and form a new star, a sun that gives warmth and light to a world near it.
Conversely, the first quasar sought to create others such as itself, and together they formed the most powerful group of entities in the universe, and the collective force of a thousand quasars radiates blue mana, almost pure Force, if not quite, such that moves the oceans and affects moons even remotely close to its leylines.
The tale of how the dark leylines radiate throughout is a gruesome one. For when the first black hole devoured a thousand worlds, it grew so big and powerful in its hatred for all matters, that this hatred began seeping out of it in spades, and so everything the black mana touches becomes tainted in one way or another.
The fiery energies of destruction that shake the earth and make mountains erupt with lava and ash come all the way from the first supernova, which in its wake destroyed a thousand stars, and the heat of a thousand supernovae radiates though red leylines still to this day.
The verdant life-force from the first nebula spreads slowly throughout the universe, crawling and jumping from world to world, as the leylines make their way across the cosmos, forming the giant web of all living things. They are through it connected to each other, and always will be.
Such is the tale of the genesis of the leylines, as recanted by the great sorceress on her deathbed, and from what little we know and observe in the sky, there is so far no reason to question it.

— Naa'ran, First book of the great explorer, chapter 11 "Mythoi of creation and other tales of old"