I can prove the existence of myself, and anything that exists only due to its definition. For instance, justice exists, if only for the soul reason that its existence is merely based on the definition of justice. Justice would therefor be different for almost everyone, but because it exists within definition, it exists.
Easier example; shapes. A shape does not have to physically exist to be existing. A triangle is a three-sided figure (plus other specific jargon), a square has four equal sides, and you don't need to see a square drawn on the bathroom wall to quantify its existence.
I could technically say God exists, but only by the pantheistic, or panentheistic (those two are essentially the same thing) definition. Even if there's nothing else, at least I exist, and therefor if I'm everything, I am this form of God, because this form of God is described is everything. Or rather, God is me, if you're going with the panentheistic one. And it is also everything else that exists, whether or not it is physical.
Someone better stop me now, I'm having fun.
Easier example; shapes. A shape does not have to physically exist to be existing. A triangle is a three-sided figure (plus other specific jargon), a square has four equal sides, and you don't need to see a square drawn on the bathroom wall to quantify its existence.
I could technically say God exists, but only by the pantheistic, or panentheistic (those two are essentially the same thing) definition. Even if there's nothing else, at least I exist, and therefor if I'm everything, I am this form of God, because this form of God is described is everything. Or rather, God is me, if you're going with the panentheistic one. And it is also everything else that exists, whether or not it is physical.
Someone better stop me now, I'm having fun.