You kill a Vex mind that tells your ghost it's afraid of the one thing in the galaxy it can't simulate: your light.

But the grimoire cards clearly state that the Vex cannot simulate Oryx and sword logic.

So… we have a contradiction. Either that or the darkness and light are actually the same thing or something. Or maybe it's a retcon.

I remember Failsafe telling me that the vex call guardians "Those who wield that which cannot be simulated" but I don't recall a mention of it being the only thing they can't simulate.

Maybe the vex actually suck at simulations, which is why we beat them constantly. That would be a funny twist.

You kill a Vex mind that tells your ghost it's afraid of the one thing in the galaxy it can't simulate: your light.

But the grimoire cards clearly state that the Vex cannot simulate Oryx and sword logic.

So… we have a contradiction. Either that or the darkness and light are actually the same thing or something. Or maybe it's a retcon.

Two points of potential significance. Both the darkness and the light have been referred to as paracausal. So...yes there may be a connection.

Secondly, the Vex were at least able to reproduce the paracausal nature of the darkness by observing the Hive and subsequently worshipping the worms. Though they may not be able to simulate it they at least have some level of understanding of it, which is more than can be said of the light.

Cody. I'm gonna need you to go ahead and do a Brokeback Mountain style trailer for a Vex mind/Guardian romance movie.

There are two underlying assumptions in your logic there:

1) The Vex minds are all-sharing between each other. You're assuming the Mind that tried to simulate Oryx shared his findings enough for this particular Mind in Nessus to know about them.

As far as assumptions go, that used to be one of mine too, until this 'contradiction'.

2) The Vex actually used the term Light and Failsafe didn't 'translate' anything before telling you. The Vex might have actually used a term which does in fact easily describe both the Light and Darkness without getting into the "the Darkness is the Light" debate. As it was pointed out above, both are described as paracausal in multiple instances, both are "granted by gods", etc.

This one is pretty easy to reconcile with the lore without breaking anything at all, IMO.

Now, if we were discussing the intent of the writer of that line, as opposed to whether it punches a hole into the lore or not, I do believe he/she might have forgotten about the Book of Sorrows. Hell, he/she might've even not read it at all.

So… we have a contradiction. Either that or the darkness and light are actually the same thing or something. Or maybe it's a retcon.

doesn't the ghost say that the shard in the EDZ is dark, or the light is gone from it or something along those lines?

simplest answer is that the light and darkness are like the Force. 2 sides to the same coin, which is why the Vex cannot simulate it.

Maybe Light and Dark are both the "same stuff", just in opposite directions. Light = positive numbers, Darkness = negative numbers. Both are "space magic" and that's what cannot be simulated.

Also, who says the Vex mind was telling the truth with it's dying [breath/computation?]?

I've always assumed that Light/Dark are the same, just opposite sides of a higher space magic form. The Traveler and the Darkness both come from the same trippy dimension mentioned in the Dreams of Alpha Lupi cards. This makes ours and Oryx's powers similar in the Vex's view.