smcj wrote:On the level of convention, there are valid, and invalid, appearances.
On the level of Truth, Emptiness, there is no need to differentiate between these objects of negation, as they are all mere appearances to mind.
That's the crux of the matter. If there is nothing other than "mere appearance" then hologram of a horse is as much an entity as an actual horse. Or rather, the horse is as much a non-entity as the hologram.
On the conventional level there is inexorability of Cause and Effect. On the conventional level, the causes and conditions for the unicorn do not exist--therefore, there is no "form" that appears as a unicorn. Of course the mind can "conceive" of one, as an idea. Currently there is also no convincing cause and effect for the hologram of the horse, though there may be in the future, eh? There is, most definitely, cause and effect for the beast known as Equus Ferus Caballus. That beast is ultimately a mere appearance, as are we.
All things are equality in the Vast Expanse of Dharmata. The horse is as much a non-entity as the hologram. However, mere appearances differ according to the laws of conditioned phenomena, and therefore the appearance of the hologram of a horse, and the appearance of the living, breathing, Equus Ferus Caballus, are two different appearances, and not equivalent on the level of convention.
As Guru Rinpoche said, "My view is vast as the sky, but my respect for cause and effect is as fine as grains of sand."