There is no Horhsalian who never heard of the Essence - except some cases of people that live completely outside of society but even those should see its influence. The Essence is such a complex and extensive subject that people fear they might never learn all about it.
Where did the Essence come from and why does it exist? Has it a mind of its own? How would the world be if it never existed?
There are so many questions surrounding it and Essence researchers/scientists try to find answers to these questions while discovering new ones that want to be answered.
The Essence is a being that is its own kind of entity - a being that most people describe as metaphysical because it does not have an actual shape in our world. Yes, there are Essence Beings, Essence Energy you can see and other things but those are just fragments of it - you can not see “the Essence” itself, which probably does not even possess a corporeal form.
The easiest way to describe the Essence would be a force of existence that is just there, something that you cannot actually explain because it functions in a completely different way than living beings do. A bit like a God with the difference that you can actually be sure that the Essence exists and has an influence on the world (this does not mean that believing in a God is bad). It is not a deity, though, which was confirmed a few millennia ago.
What we do know is that nothing in this world had and has so much influence on Horhsal like the Essence. The state of its continents and all the fantastical things happening in them - most of them exist because of the Essence's influences. For example, the random weather and climate in Rimsal. The Essence even influences Post-Eophrims and numerous animals and monsters but apparently does not influence Non-Eophrims that much or at all, depending on the race.
There are various powers and abilities the Essence can grant to people, such as the usage of Essence Pleas, Aptitudes, indirectly through Essence Cores and Solid Essence , and through other means, all possessing their own pages here in the Essence section.