@boagie,
Shostakovich,
See this is the thing. We do not even know if there is an arrow, at/all, let alone if it is moving. What if it is a ‘dream arrow,’ much like we might come upon during REM? Then does the arrow have any material substance, or can it lay claim to any spot in space, or is it actually flying about in our bedroom, having motion? Proof during a dream would be insubstantial, after all would it not be dream proof, here and now, but “POOF,” gone upon waking?
Yes, “They are "suppositions" of the intellect,” and where does it stop? But not impossible to comprehend, even if it did turn out to be a dream's comprehension.
A good deal of what we comprehend is not necessarily true to what we believe it is. Most of what we think we know is simply patterns decided upon somewhere between our senses and our brain, and even the brain and our senses could easily be dreamed up instruments.
Beware of intuition. At what point does intuition become imagination?
This is why some people avoid metaphysics like a plague. Others of us take it as a challenge to both be alert and investigate these things personally. But you must be willing to let your investagation take away everything you thought you knew, and even if it comes to this leave you naked and alone.
This is the “Dark Night of the Soul.”
This is Socrate's wisdom, because of he knew that He didn't know.
This is where we step off the side of the earth or transcend.
S9