Magic is an inherent part of the world. Unlike many D&D settings, there is fundamentally no difference between arcane and divine magic. Living things radiate low levels of magic by simply existing, and this energy is what is typically harnessed to cast spells. The difference between arcane and divine magic is not the source of the magic, but the means of harnessing it. Divine magic involves the caster attuning themself to the world around them to find the right sort of energy for the spell, and directing that energy in a favorable way. Arcane magic involves the caster taking the energy and bending it to a specific purpose. For simple spells, arcane magic is easier, as magic is inherently malleable, and to be shaped, the caster need only have a stronger will than the magic itself. For very powerful spells, divine magic is easier, as an accomplished divine caster can seek out magic that is already inclined to do what the caster wishes, and need not challenge it.