Philosophy Bookshelf: Whom do I include?

Having filled my philosophy bookshelf, I am presented with the need to reorganize it in order to find room for more books.  Obviously, texts shall be first organized by philosopher (Plato, Spinoza, etc.) and then by the philosopher's date of birth.  The problem is that I have to decide what counts as a philosophical text.

Currently, the texts of Sophocles, Euripides, and Aristophanes are on my shelf.  Since I purchased these texts for philosophy classes, I placed these texts upon my self within the Greek philosophy section.  Yet now I wonder if they deserve a spot on my philosophy shelf at all, given that they are not technically philosophy.

My main dilemma is that I want to include Aristophanes, because I really like The Clouds. Since Socrates is a character in his play, I could categorize Aristophanes' work as philosophical.  But if I include Aristophanes, I am obligated to include Sophocles and Euripides.  If they are included, I probably ought to include Ovid as well.  And then Gilgamesh, and the list goes on and on as I continually add more literary works from antiquity.

The question is further complicated when I try to assess the works of Dante.  I took a seminar on Dante in which we compared his works to Aquinas.  While Dante does not articulate a philosophy, he does invoke themes from Aquinas when crafting his narrative.  Additionally, I have the Lectura Dantis texts that touch upon the philosophical tones of the plays.  Do these count as philosophy, philosophical, or some third thing?

This seems to be a tension I could use in order to make this decision:  We distinguish philosophers from those who utilize particular philosophical ideas as components of a story or some larger project.

However, if I make a distinction between those who do philosophy, and those who use philosophical ideas, how then do I organize my books on mathematics?  My books on infinity and zero utilize philosophical themes, but is mathematics philosophy proper, or an outgrowth of philosophy?  If it is merely an outgrowth, that makes it akin to Dante and Aristophanes, who seem to not merit space upon my shelf.

Further complicated the mathematical issue is the text 'Geometry and Chronometry in Philosophical Perspective'.  It has "philosophical" in the title, and yet it is about mathematics.  Does it get a spot?

I'll probably lose some sleep trying to figure this out.  If the internet has any suggestions I'd be happy to read them.