Atreyu wrote:What metaphysics tells us about the world is that the vast majority of it lies outside the boundaries of empiricism...
Point from the above is, with Philosophy we have one leg on Science and one leg on speculations that are extrapolated from the empirical. i.e. the empirical possible.[b]Bertrand Russell[/b] wrote:Philosophy, as I shall understand the word, is something intermediate between theology and science. Like theology, it consists of speculations on matters as to which definite knowledge has, so far, been unascertainable; but like science, it appeals to human reason rather than to authority, whether that of tradition or that of revelation.
All definite knowledge – so I should contend – belongs to science; all dogmas as to what surpasses definite knowledge belongs to theology.
But between theology and science there is a No Man’s Land, exposed to attack from both sides, and this No Man’s Land is philosophy. Almost all the questions of most interest to speculative minds are such as science cannot answer, and the confident answers of theologians no longer seem so convincing as they did in former centuries.
Metaphysics is when one take a leap from that 'No Man’s Land' into a bottomless canyon into the realms of the empirically impossible into theology and illusory ideas.
Paraphrasing Kant's view, Plato was doing metaphysics like flying a kite without any attachment to any empirical strings.
What is realistic is even though without solid empirical proof, whatever that is speculated must still be attached to the thinnest of empirical strings. Without any empirical strings, it is merely an illusory idea. i.e. metaphysical.
Metaphysics whilst impossible empirically is only possible in one's psychological world to generate psychological security.Kant insists that “metaphysics is utterly impossible, or at best a disorderly and bungling endeavor” if we do not separate “ideas of reason” from “concepts of the understanding” (Prolegomena §41, 4:329).
https://plato.stanford.edu/entries/kant-reason/
Thus to understand 'what is Metaphysics', one must understand the related human psychology.