Saidin

Saidin is a form of energy that can be harnessed by certain individuals to create spell effects and magic items. The ability to manipulate Saidin is very rare among mortals since ancient times, and it has only ever been documented in males. Thus, some have named it the "male energy" of the universe, in contrast to Saidar , which has only beed documented as malleable by female individuals, also called the "female energy" of the universe.
Those with the ability to manipulate Saidin can feel it very acutely during the spellcasting process. All individuals describe it as a "torrent of fire", or a "rushing river", or other definitions reminiscent of an aggressive force, capable of sweeping one away if not handled carefully. The only effective method of accessing Saidin known presently is to forcefully seize it and command it. It is a force that needs to be guided forcefully.
Scholars also agree that Saidin is very tempting, since accessing even a small amount can feel very pleasurable. Those that get carried away either die as a result of accessing more of the Saidin energy than their bodies can handle, or lose the ability to access Saidin completely.
Male spellcasters typically train their ability to access Saidin for decades, only marginally increasing the amount of accessed energy as their study progresses.