Andrew asked:

What is Metaphysics and how do we use it in our personal lives? Also who was the first person to
come up with this theory, how did they find it and how did they use it? What do philosophers use it for
today?

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Metaphysics is not a theory but a type of inquiry — an inquiry into that which underlies appearances.
What is it that truly exists, and causes all that we experience? No-one came up with this — or if
someone did, it is lost in the mists of time when humans first started to become self-aware. Such
questions are asked in many of the earliest writing we have. However, the name 'metaphysics' comes
from the fact that Aristotle talked about such questions in the book that comes after his 'Physics' —
and metaphysics means (roughly) 'after Physics'.

We use metaphysical assumptions when we see the world as made of certain types of things — say,
only of 'atoms and the void', or of two types of stuff — matter and minds, and so on. We may not
actually inquire into these assumptions of ours, but they are metaphysical.

Tim Sprod