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A metaphysician strives to gain the most general knowledge about existence.
His or her concepts could not be proven true or false.
He or she is not able to provide any explanation how things work. This has to be done by scientists.
A metaphysical system, devoid of any content in itself, enables the philosopher to arrange all gathered information about the world, to see experimental knowledge from an interesting, sometimes even astonishing perspective (for example that the universe is but a dream). It could be compared to a transparent vessel which gives shape to a set of different, colorful jellies.