First. Pray tell me something about Metaphysics, for I cannot for my life make anything out of it.

Second. Metaphysics is the science of abstractions.

F. I am no wiser for that definition.

S. Well, take for example this earth. Now the earth may exist.

F. Who ever doubted that?

S. A great many men, and some very learned ones; although Bishop Berkeley has proved beyond all possible gainsaying or denial that it does not exist.

F. That is a point of considerable consequence to settle.

S. Now the earth may exist, and—

F. But how is all this to be found out?